Optional 'make an offer'

Sometimes I want to sell something for a flat fee and people end up offering on my trade despite that. I want there to be a feature where the 'make an offer' feature is intact by default but can be turned off by checking off a box that says something under the lines of "Turn off offers for this trade?" and a box to check off. I feel bad declining trades from people, even if they offered me something I did not want.

Seems reasonable, support. Offers can be a bother if you don't want them.