A buddy of mine just picked one up in good condition. It only has about 1000 miles on it. He paid $2000 CDN. Good deal IMO.
The 470 Rotax is a bullet proof motor. I've had MX's from the late 80's with over 10,000 miles on them and they still pulled hard on the lake. The ST isn't the best trail performer, but it's a good sled if you can get it at a decent price.