If that's indeed a trek 420 mixte (and I have no reason to believe its not), I think its a pretty nice little bike. We had a blue one in our shop about a year ago and it was pretty cool. It appears to have a nice lug at the seat tube top tube junction (many are cheesy) and it has a brake routed to the central set of stays rather than the top set, this is kind of a neat little feature. It also appears to have a deraileur hanger, which would be a sign of a nicer bike in that age bracket. Its an odd bcd, but it does have a triple crankset.
anyway, it may be a little over priced, but I think it'd be a great little bike with some work (and a new seat).
Michael McDonald
Burlington, Vermont