Proving that you own the domain is not hard, agree on something, create a txt file, then upload it so he can see proof on what you agreed to upload....
Exactly, he's telling me that these certificates verify that I own the domain which he already ask for a screen shot which i dont mind sending him with some of the things blurred. So when I got to the website he is giving me, I have to pay for that....? Any other thoughts?
Some registrars provide certificates to their customers (just a .pdf or something where it is written that John Does is a registrant for johndoe.com). But most registrars don't do that. The only thing that really proves that you are the registrant is your information in Public Whois, and this is stronger than any certificate.