If you were to post a firearm and I say "I will take it", how long would I have before I need to pay you? One day? Two days? Two weeks?
Does the "I'll take it" allow me to dictate terms to you or do you still reserve the right to refuse the sale if my terms are unreasonable to you?
The point I am making is that a "I'll take it" is not a absolute conclusion. It is simply the opening move in a negotiated sale. If I have two willing buyers, and buyer #1 wants to add burdensome demands (I can pay you when I get my tax return!) as part of the sale and buyer #2 does not, I am going to sell to buyer #2. I apologize if that ruffles feathers....its just business.