I bought a 2007 Bet&Win 150 with 3,000 miles 2 months ago for $1,700. It is great around town (up to about 40 mph). Quite stable. I absolutely love being about to put my feet up on the sloped foot rests while driving.
I've had it on the highway up to 60 mph 4 or 5 times for 20 minute stints. The ride is stable but the engine is up to about 9,000 rpm at that speed (kinda pushing it). Also, my speedo is about 10% optimistic and I have to keep doing math to make sure I'm not speeding. I think that's the case for most scoots though.
All in all, I'm happy with my purchase.