I never asked for a deposit for any boat I sold. Most buyers come from a good distance away which makes them serious to begin with. You've probably had a few phone conversations with them too and can get a good feel. There aren't many buyers for boats like these in good times let alone in this economy, no sense in busting chops. Last, I'd never put down a deposit myself to get a ride on a boat I'm considering buying. I figure if the seller can't tell I'm serious enough to drive 100s of miles (or fly in one case), have multiple conversations on the phone and probably some emails with them then I probably don't want to deal with them anyway.