People have been doing similar scam on used car sellers for years.

Example being I post a car for sale. Scammer offers to buy. Scammer brings check higher than the agreed price. Tells me I can deposit the whole check, just give them difference back in cash. Scammer leaves with that cash and the car. Few days later bank tells me the check was no good.

Used to hear about that often enough Craigslist even sent out warnings to sellers.