Trading between players is the game
Trading is not deviant behaviour. It is the game. The market is internal, with double-confirmation escrow, a fee burned at listing, a progressive tax by bracket and a public price history. The premium currency is tradeable between players, and nothing it buys is exclusive to it: everything circulates.
Money comes in, money does not go out
That is the line that is never crossed. There is no withdrawal, and no conversion back into real money. It is the same line that separates healthy sanctioned economies from parallel markets.
The floor is the counter, not the market
The price floor for everything is the fixed value at the Order's counter, never indexed to the market. Indexing would be printing currency. The character who runs that counter states the thesis: The Order tells you what the thing is. I tell you what someone pays for it. Both are true and they are almost never the same number.