I really like this idea, of course it comes with ups and downs. I don't have enough information to fully create an opinion on the player shops, but if all proceeds are going to the player, and they are "player shops," I think that you might have to pay to have a player shop. Hypothetically, if that were true then I think you shouldn't have to pay up front for the player shop. But instead, depending on how popular the area where your player shop is, a certain % of the proceeds should go to the proprietor. That way, rich players won't always get prefer getting richer via the economy, and reserve the best areas to sell. If that is not the case however, as I said earlier I don't have enough information to go off of. I simply think that is a good idea. An auction house is a good idea, but I think there should be set values you can price certain items, so that players can't troll by renaming an item to something inappropriate or stupid, and selling it for a ridiculous price so that nobody will buy it. In my opinion, you should make it so that player renamed items cannot be sold in AH, and there is a bottom and top price for specific items in this AH. (AH being Auction House) Direct player to player trading is a no brainer. Its simply necessary. But a suggestion I have is that when there is multi-world support leading to this in total "Universe", you should be able to still player trade through different servers. That is all I have to say about this system, anything you would like me to elaborate on just dm me on Discord.
-Des