If the dad has an extennsive
eBay history ask to see if they will make an
eBay listing with your
eBay username as the only person authorized to bid on the auction so there is inarguable proof that the deal was done as there will be the record of you placing the bid on
eBay's servers then the record of your payment on PayPal's servers (probably the same servers as they are the same company) in the unfortunate event that you have to make a claim later (hopefully this won't happen but yanno - just in case....)