I'm going to assume that you are willing to break this down into chunks, or is that not the case? I would be interested in exchanging about $100 of your Paypal for my BTC. I'm going to assume that you're willing to send it first, since your method is reversible and BTC is not, is that a fair assumption?
Escrow is the best way if you don't trust each other.
if you don't believe in sending first, don't ask people to send first, use escrow this is fair