Quoted from Coz:IF I’m serious about buying a pin, i will send you a PayPal deposit. It shows I want it and for you to hold it for me. I’ve also bought and sold with no deposit, it is hard to trust people you’ve never met.
Agreed, Some people think deposits should be refundable. So it seems pointless to collect one these days. However a deposit is designed to say "I am putting money in place as a promise that I am holding up to my end of the agreement or you get money"