I saw an ad for a 2006 ktm 125sx for only $1900. Would you be suspicious of this bike having problems with a price tag like that? or is that about the right asking price for a bike like that? what do you guys think of ktm in general? I was looking more at a yamaha or honda 125 but if I can get a 2006 for only $1900 why not?

I am ALWAYS suspicious of a used bike. If it looks ragged out ask if you can take it to your mechanic and have it looked over. As with any used bike plan on doing at least the top end and a thorough inspection of the entire bike. I would pull it down to the frame and check very closely for cracks or stress marks. That being said, even if it needed a complete rebuild and some frame welding it would still be a decent deal.