I'd find a "Sponsor" system fun. You pay a certain amount of ROBUX, and then be allowed to add one item to the catalog. Of course, you'd get the item free, but have to pay a 1K or so base fee plus double the cost of the item.
Eg. Say I make an item called "Cape of light", and price it at 4K robux, I have to pay 9K Robux. |