Instead of making a t-shirt for buying your place you should be able to go to the places section in the catalog and looking at the "for sale" section ad it says like... (for example) Nuke the whales: 100 tix 25 bux.
To sell a place you just make a shirt and sell it for the amount the person is paying you, then when the person who's getting your place buys it you make a Free Model so he can take it.
I think this is a bad idea, what would happen when the other person bought it?
The buyer and the maker would have it even if when you sold it dissapeared from your showcase, its still saved as a "rbxl" on your computer.
-☆Дle✖2266☆