This was never brought Up. Since in epic. The training market is not as effective as in the oficial game. But u do have a point. I think aga should be able to edit the shops. But with so many things he gotta change this usually falls into the pile of changes when he does have time. Try to be patiente and keep this topic alive so aga can remember.
I'd like to add that the training market is not as effective in the official game because here we move way higher quantities of money and the limits imposed on buying things or selling things via your own stall are too low.
For example if I decide I wanna make a Warsong belt and try to buy WWI via my own stall, the maximum I could buy is 1 because they are worth around 150m in money and the limit is 200m. I need 60. Totally pointless right? if the limit was removed I could buy via my own stall 60 of them because I have plenty of bank notes saved.