So... we have an actual marketplace now for buying items back from the server. The prices aren't quite set in stone yet (I need to revise them after some sleep) and some key items are missing, but the basics are working.
The booths are themed to represent the items available there for purchase. To buy an item from the server, right-click the appropriate sign.
Some prices will be deliberately inflated. This is to encourage normal resource gathering in favor of sitting in front of a cobblestone generator and cashing out periodically.