If someone wants to buy that design is up for auction for 2 hours, anyone can offer higher and the auction ends 2 hours after the last person bids or buys. Starting "bid" is 25 points. These designs can be modified.
For example.
Person #1: wants #A for 25 points at 1:00 PM
(no one offers) 2 hours pass, #A is sold to Person#1 for 25 points
or if Person #2 offered 30 points then 2 hours has to pass for their offer to be completed.
This allows a fair chance for anyone who wants to buy a design.