Since so many in this group sell via the web, I thought this article would be of interest.
formatting link
For those that can't get the article, the jist is this: A buyer contacts the seller with the prospect of a large sale, and offers to pay with a cashier's check. The check is for a larger amount than that of the sale, and the vendor is told that the extra money is to pay for "shipping." The vendor is then instructed to wire the "extra" money to a shipping agent. However, the cashier's check is a forgery, made on a laser printer. The whole scam is out of Nigeria (surprise, surprise), and the government there is powerless to control it.
The amounts aren't in the millions, like some of these other Nigerian scams. A huge amount of money would definitely raise some suspicions, but a couple of thousand probably wouldn't. OTOH, losing a couple of thousand dollars isn't fun at all, and could be financially devistating. Be careful out there. Kathy N-V