I'm sorry to hear that you have encountered some problems dealing with another PbNation member. If you could post screen shots of your PMs and PayPal receipts (if Paypal was used), with any personal information removed, it would greatly help. Posting this information is a requirement for making a theft report.
Please see the Theft Report Sticky sections 3 & 4
for more details and what information your theft report should contain and how to take/post screen shots.
After that information is posted we will be better suited to help you.
In the mean time, have you tried calling him?