It's pretty weird that you (16 years old) are asking $3000 - $4000 from a kid. However, I know how annoying these people can be and they really don't take no for an answer.
I once blocked someone similar and he just kept e-mailing me while he knew I blocked him from MSN.

And I really don't think this guy now understands how much time design/development takes after you showed him some websites of companies.