ACCEPTING PAYPAL IS NOT SAFE!!!
Others are saying it's safe if you get payment through paypal, but that IS NOT true...
For starters you have to post it to a verified address, if a paypal address is not verified or he asks you to send it to another address, you're not covered at all! And the limited cover doesn't stop there... I'll tell you about my experiences later... But first....
Tell him you will only post to the UK, no international buyers - it sounds dodgy, so don't risk it.
In this situation, it's probably a stolen american credit card, and the theif lives in Lithuania... The address he'll want you to send it to will probably be a deralict house or a PO box.
Anyway... If you accepted a payment from paypal, and later it turns out to be stolen, paypal will reverse the payment, so you will be out of pocket. Many people think paypal is safe due to all the paypal safety adverts, but after all the small print you're actually covered for VERY little... I learnt this the hard way....
Firstly, I got ripped off through paypal when buying a memory card from hong kong... I paid £30 for it, and after never receiving it, I processed a claim... the claim was awarded to me, but paypal couldn't recover my £30 because the seller didn't have any balance in his paypal account and a request from his bank bounced.
Second time, I was the seller... I sold a sky plus box for £80... The buyer said the box arrived with a brick in it and no sky box. A paypal claim was processed by the buyer, and I replied with my side saying the box was sent recorded delivery and the sky box was securely packed. The claim was awarded to the buyer, and the payment was reversed. I lost out on £80. I considered claiming through the post office, I rang them and explained the situation, that apparently the sky box had been replaced with a brick, and they said I'd have to provide proof that I had packed a sky box and not a brick... I asked how do I proove that? They said I should have a packing slip and a receipt of purchase for the item and would have also been required to have sealed the box with security tamper-proof tape. Well, as a private seller I don't have my own tamper proof security tape, so they advised me the claim wouldn't be accepted.
So..... Basically, if anything sounds dodgy, don't risk it, you're likely to lose out.