He sent me enough to show he was serious via venmo. In this particular case I have decided to make it refundable. He's working on selling his boat, I'm not in any hurry to sell mine. If I needed to sell mine to get another one I'm sure I would have decided to make it non-refundable. We are both busy this next weekend, and he wanted to get it off the market so we agreed to do that once I received his deposit. If he backs out, maybe I look stupid, but I'll send him his money back and list it in the spring. I try to treat others as I would like to be treated in this scenario, so far it hasn't bit me.