Hmm, I don't want to go into an economics lecture, but you are wrong on both statements.
No rational player would buy a BAR for over 200k, because they could get it at the store at anytime for 200k.
You can't make a profit when no one will buy your gun for more than 200,000.
There will be players who would sell for less than 200k. These players are the ones who don't want the BAR anymore and would rather have/need the cash for a new gun or whatever reason.
The issue around a no trade system in the game is not because we can't develop a trade system, or the GUI for a trade system... it is because the developers don't want a free economy where players can capitalize in certain assets, whether it's gun or money. In an open market, the demand of the guns are determined by the supply of the guns (supply is infinite in our current system). Prices are set by the developers in our current system. If we allowed trading of guns, in the long run the prices of guns would greatly decline way below the shop prices. Which implies no one will buy from the shops, which implies that the money is only circulated between the players.
This is an issue for any game industry. If money circulates only between players, and players are constantly making money via shells/gralat packs, pretty soon we would have TONS of money supply in the economy. There are a few issues associated with this. If players can buy the gun cheaper off another player, they would not buy from the shop. This means the money spent on the gun REMAINS in the economy. In our current system where the player is forced to buy from the shop, the money DISAPPEARS when it is spent on shop items. This results in reducing money supply, thus increasing demand for money. Increased demand for money means players buy gralat packs, which means revenue for game developers.
Basically, less guns being bought from shops = less revenue for game developers. How to prevent that? Not allowing trades. By not allowing trades, players are FORCED to buy their guns from the shops. Again, when they do this, money is taken out of the economy since it just goes to the game server (rather than to another player). When the player wants another gun, he can't simply sell his old gun to gain money and buy another gun, he has to get money buy either working (shells etC), or buying gralat packs.
Why not just limit the supply of guns? ie have a set amount of guns in the economy? You'll run into problems with item hoarding, and the difficulty for new players to obtain new items. Difficulty for new players to compete with the current players, will drive playercount down, which results in a decline of revenue for developers. If you ever have the chance to check out PC Graal Kingdoms, is is a GREAT example in a failed economy. That game's main currency is not even used as the primary currency. It is not a coincidence...over the past decade, PC Era has had numerous server resets (due to inflation) and an uncontrollable economy. Graal Kingdom suffers from an overly inflated economy and item hoarding (nearly impossible for new players to get their hands on decent items, which drives them to stop playing).