Sadly, this is exactly how they work. They do it on ebay as well..set up accounts and gain a few positive feedbacks & seller ratings (many of which are simply from their other fake accounts) then..whammm...rip off dozens of buyers all within a few days.
Account gets flagged and shut down, but they simply move on to thier next ID.
OP, if you have his mailing address, send him a registered letter, asking for a full refund or the part shipped (pay or surrender), provde a reasonable deadline (normally 10-14 days from receipt of letter) IF something has happened, like a medical issue, then someone at his address is most likely receiving/handling his mail/bills, and they would certainly contact you back.
Failing that, you will have to go scorched earth on him ( I outlined steps in another thread about a rimblow steering wheel rip off)...if you sent a U.S. postal money order, that could well be considered postal fraud, interstate commerce fraud, theft, etc.
