On Wednesday, December 6, 2017 at 3:26:52 AM UTC-8, Casey wrote:
...the guy is ... sending a cashiers check and arranging shipping...

Just to go all Captain Obvious on this one, the way this scam typically works is that the check is fake, and usually written for an amount greater than the price of the goods. The check looks real enough that the bank accepts the check for deposit. But a day or two later when it turns out that there are no actual funds behind the check, the bank simply (and rightfully) declines to deposit the non-existent money in your account.

The expectation is that you will send them cash or a wire transfer for the overage before you find out the check is fake. They get the goods and the extra money, and you get nothing. For something awkward like a glider, the "shipping arrangements" are often fictional, and all they're after is the money.

--Bob K.