I've been burned a couple times with saws on eBay. The first wasn't so bad. I got an 011aveq for $40 described in fine running condition. It actually had a bad piston, low compression, and an air cleaner that hasn't been looked at since it left Germany. It's waiting for me to get off my tail and fix it.
The second time was a real doozy. Bought an 026 that supposedly was in terrific shape and great, but the coil was removed for another saw. Well, at least the last part was right. The box it came in had been cut open and gas was leaking all over the place from a broken vent. This thing looked like it had been seized up and then dragged behind a truck going cross-country. Boy, that piston was bad--the rings had melted. I even found a rental sticker after I cleaned some of the dirt off. It was totally wrecked and only good for some internal and housing parts. Paid $75, kept the bar, chain, and air filter, and sold it for around $50 with an honest description.
Always ask lots of questions and make sure you have good photos, unless you can't lose at all. You might get lucky, I did once.