One thing I've learned in life, and in transactions...you lose the most from those who have the least to lose. If the buyer has no ethics, reputation, money, nor a credit card that he really cares about keeping...it's too easy to pull a "not authorized" chargeback. Gift, goods, signed paper, doesn't matter. Credit card company reverses payment to Paypal, Paypal reverses payment to you, and if you already withdrew it to your checking account, they'll lock your account and do everything possible to get that money back. So if you don't care about your Paypal account, legal notices, etc. (in other words, if you have less to lose), you don't have to worry
But realistically, this doesn't happen that often so you're probably fine. Cash can be a risk too. Go with your gut. But if you tell him no, especially now, then even more trust is lost among strangers and with both parties suspicious of the other you could lose the transaction.
For the record, my preferred method of payment anymore beyond a couple grand is wire transfer. I give an invoice/receipt, they pay right into my account, machine ships or is picked up right away.