A couple years ago I had a guy try to scam me on ebay...I was selling a Line 6 Flextone. Prior to the sale, he emailed me and asked if the amp worked, because he had "fried" his other one. I should have known then.
To make a long story short, when he got the amp, he claimed it "shocked" him and ruined his guitar too. I went through about 6 weeks of hell fighting the Paypal claim, and found the guy on Myspace too believe it or not...lo and behold, he had a picture of his "new amp" and the guitar that supposedly got fried.
Bottom line: he was going to send his "fried" amp back to me and was going to keep the one I sold to him. Luckily, I always keep a record of the serial numbers of anything I sell. I won the Paypal dispute and also filed charges for fraud. The charges never went through, but he did get a couple letters from his state's attorney general's office telling him I filed a complaint with them.
Nonetheless....I learned a valuable lesson about selling items...I watch and see people's feedback scores..if they have more than 1 negative, I cancel the bid. If they have a "0" feedback, they have to contact me first, and I ONLY accept Paypal and ship to a confirmed address.
Chances are you're probably okay with this sale, especially since you have the money order. I've also had some slow payers, and I believe ebay makes you give the buyer 10 days before you can cancel the sale.
Best of luck...glad you got the money order!!