Ask HN:Payment Platforms for Validating Users
russell: You should remember the transaction charges.  I think most payment systems charge 20-30 cents per transaction.  I dont know about PP.  I don't have a PP account and would probably object to giving you my CC number unless I found your service compelling.  I certainly would not give it just to look around.  This would probably turn off lots of potential users.  Even an email validation is a turnoff, but not so bad as a CC number.