from what I know, the game is attempting to shifting towards a skill-based gameplay and I am also aware that there is an increasing number of players of whom many are getting the once rare weapons/ items that only few have. This makes the game increasingly competitive and those who are new to the game may find it difficult to progress while the veterans will progress by leaps and bounds. So perhaps the game can have constantly and automatically changing pricing systems that regulate prices based on the rate at which it is purchased.
E.g. if one day 23 m4s are sold while the other guns remains at a low rate, then the m4 prices will increase by 23% (just for example). Then, this will reduce the number of m4s being bought and players will turn to other guns/ not buy at all. The infated price of the gun will then drop according to the decrease in its rate of being sold. The prices can also be deflated if its in low-demand, but maybe there will be a threshold to the deflation/inflation. The same can go for the prices of items and etc.
Hopefully this will be able to moderate the number of "good" guns/items that are being bought as if too many players are armed with these guns/items that will put them at a distinct advantage from those who do not have the item.