I don't know Paul. I've heard that a bank, which has already credited an account on a forged check, coming back and taking the money back out of your account. In once case I heard of, the bank actually prosecuted the depositor, even though he was concerned prior to the deposit, and asked if the check was valid. My rule would be to avoid ANY transaction where the buyer wishes to provide his own shipper, and to require significant proof of identity to anybody who wishes to buy outside of "normal" channels. Unfortunately, that is any purchase of original art on FAA.
You should definitely read this link if you think waiting for a check to clear is a "safe" strategy:
Bank of America Bad!
I would definitely go the route of requiring a check to clear, and beyond that, I would discuss your concerns with the bank to verify that it will not come back on you after the check clears. Have you considered a credit card transaction?
Most schemes of this sort involve sending you excess payment, and having you pay back the excess, in some manner.
Any request which involves you paying anything for anything should be treated as extremely suspicious.