Hello.  As I'm sure you know, we have been suffering from a 10 year dry spell do variously to consoles and some rather unfortunate business practices by big game publishers, but this is showing signs of ending, and you have already mentioned two of my favorite signs of that.

"Old" games (by which I really mean approximately pre-millennium):  I think the big two with trading to check out are Wing Commander Privateer and Freelancer.  Freelancer falls very far on the arcade end of the "simulator" spectrum, but it is pretty universally loved.  I have wonderful memories of it, but admittedly when I played it about a year ago I found that it did not seem to age quite as well as I had remembered.  It has been longer since I played Privateer in earnest, but this is also universally loved, so you don't have to take my word for it.  It is basically Wing Commander with trading.  If you have been following Star Citizen then you've probably already heard a lot about both these games as they are both by Chris Roberts, so I won't expound their virtues further.  In my opinion these games are both better than most of what has been out in the last 10 years of any genre, nevertheless if you are expecting a 1999 Star Citizen then perhaps you should temper your expectations a bit.  You can get Privateer off GOG, Freelancer is relatively hard to find these days.

"New" games (by which I basically mean since 2005): Well sadly there are few because of the aforementioned Dark Ages of Video Gaming.  In my opinion the three "playable", "modern" (by which I mean "modernish") games which can be considered Elite-type are:

1) EVE Online.  My personal pick for best game so far released, but admittedly it comes with the many pitfalls of being an MMO.  That more than anything else is the reason I'll likely ditch it altogether with the exciting new releases in the next couple of years.  Better to check out their website than have me explain it.

2) Evochron Mercenary: This game is VERY obscure (maybe less so on SSC) but is available on Steam.  It is an indie project by a single individual, so graphics could be better, but sometimes it looks surprisingly pretty.  Really many of the Elite-type mechanics of this game are quite poor, there isn't much variability in things to buy.  There is a huge region to explore and lots of goodies to be found, but sadly there really isn't an comprehensive system for doing so.  For me the real reason to play this game is that it is a truly excellent simulator.  Thankfully it has realistic physics.  It takes some skill to learn to fly well.  Anyway, even if you find the trading mechanics poor you will undoubtedly have a ton of fun dogfighting.  You said you didn't care much about combat but I couldn't resist mentioning this...

3) X3 (Reunion, Terran Conflict, Albion Prelude): I have somewhat mixed feelings about X3.  Surely it is a terrific economy simulator, the closest thing there is to "single player EVE" and you can spend half your lifetime building stations and managing supply chains.  It is often a fun space flight simulator, but not nearly as much as say Privateer, like Privateer it has arcade physics.  The one really big problem with it is that the user interface is TERRIBLE.  Every little thing you have to do, and there is a lot, is an absolute hassle and you will spend countless hours navigating some of the most terrible menus you can imagine.  It makes the EVE UI look like the Sistine Chapel.  Admittedly you get used to it somewhat, so its definitely worth playing, and for a hardcore space-sim/elite-type fan it's an absolute must.  I probably have in the neighborhood of 500 hours logged on the X3 games total.  If I were you I'd get Albion Prelude as it is the most recent.  You can usually get all the X games on steam for very cheap.  Anyway, the graphics for these games have held up extremely well.

Very soon there will be X Rebirth (sequel to X3)!  There are for some reason a lot of naysayers about this game, perhaps due to the aforementioned problems with the X games.  For me, it looks better and better the more I see of it, so I am just about bouncing off the walls in anticipation for this one which releases November 15.  Anyway, this one is what I hope to keep me most busy until Elite and SC.  If you are looking for good graphics, it looks absolutely gorgeous.  I admit, I am not yet totally convinced that the UI will actually be "good", so that is my biggest worry.  Nonetheless, from the look of everything they've released so far it seems that at its absolute worst it will be marginally better than X3:AP, which, while it would be disappointing, that's still hundreds of hours of engrossing gameplay, so don't listen to the downers!

Lastly, I think Privateer is the one that will most make you feel like Mal Reynolds 😉

Good list here http://massively.joystiq.com/2013/10/20/stick-and-rudder-ten-space-sims-to-fill-your-star-citizen-void/ although they are not all space trading games and I would remove DarkStar 1 for something better like Hardwar or Terminus.

As for more modern games their is the aforementioned Darkstar 1 which is a basic Elite clone as is Galaxy on fire 2 and come to think of it so is Spaceforce:Rogue Universe you should be able to find them on GOG or Steam

Also worth a look is Dangerous at http://whoisdangerous.com/

Precursors but only if like playing an unfinished games with bugs

Drifter the games not finished yet but you can get access to the beta version http://celsiusgs.com/drifter/

Ring Runners http://www.ringrunner.net/ nice 2d one

have a surf through here http://spacesimcentral.com/ssc/forum/6-spacescifi-combat-and-simulation-game-discussion/ you will probably be able to find something of interest but as ExpandingMan said above you may be better off waiting for X-Rebirth as it seems Egosoft have done good with this one.

Played countless of X3 albion too. Add in some nice mods and it becomes a really fun game. X rebirth is eagerly awaiting to be preloaded in my steam list. The X games have often been somewhat to quite buggy though on first release. X3 reunion was notorious for that. The UI, as mentioned above, is very daunting.

Oresome is a little known one, still in alpha. But the dev is making good progress and I also poked him about some issues in the game and the next patch it was fixed.

For sale here:  http://www.desura.com/games/oresome

Others worth mentioning:

http://www.moddb.com/games/star-trek-excalibur

http://www.moddb.com/games/pulsar-lost-colony

http://www.hazeron.com (MMO, 'pre alpha' or rather a hobby project of 1 person).

http://www.moddb.com/games/sublight  Very interesting to keep an eye on.

http://www.moddb.com/games/voidnex-frontier

Limit theory (has a thread on this forum).

Star sector (formerly spacefarer).

Of course, the new Elite and the upcoming Star Citizen are worth a mention.

Last but not least:

Some are not exactly a 100% fit with your description, but they might be enjoyable none the less 🙂

Vendetta Online:

http://www.vendetta-online.com

New player guide

I've been a Vendetta Online player since June 2003; it is a very worthwhile game, and one I'm planning on sticking with for a good time to come.  The main reasons I play are the community, history, physics of the game, and culture surrounding the playerbase:

Vendetta Online - Lucid Dreams

Another important reason to play is the device-agnostic approach the devs have taken in porting the game to mobile; I can, for example, mine some rare ore during downtime over my smartphone, then log on to my laptop later on to guard a trusted player I've hired to transport this ore to a different location where I plan on using it to manufacture capital ship components or rare weaponry, etc.

The game follows mostly Newtonian physics, with a few artificial limits in place to increase playability.  The devs are tentatively aiming for a gameplay expansion (version 1.9) Q2 this year, and a much larger expansion (version 2.0) in Q4.  Vendetta already supports the prototype Oculus Rift.  The economy is dynamic and follows the basic laws of supply and demand, with both random events and player activity affecting the station economy, and a higher tier of manufactured / rare items traded player to player.

No mention for Escape Velocity and its ilk?

(formerly spacefarer).

it's Starfarer.

No mention for Escape Velocity and its ilk?

 

 

it's Starfarer.

Escape Velocity was a great game in it's time; it was one of my favorites when it was released, especially as a Mac gamer in the 90's.  EV:Override and EV:Nova were also very enjoyable.  I even spent hours and hours (never realized how much time I had as a kid) modding the original Escape Velocity with my own missions, star systems, and content: I even went so far as to design primitive 3D models with lighting, textures, and all that I grafted into the game.

Many of these mechanics (trading in a changing market and player contributed content) are also reasons I've stuck with Vendetta for so long.  Vendetta has the added benefit of being "modernized" with it's cross-platform galaxy and extensive 3D environments.

I know allot when ur trying to find a decent space sim, with a economy and the pirating and something to do more then flying around 😛

After days days of "hard physical work" 🙂 i foun a interesting one... maybe it is a indie game from a not well known dev...

But Starpoint Gemini 2 looks like it can be the one, a space sim with rpg elements and a hell of a lot of stuff to to... buf for now its in beta in early access...