Other than finding out if any upgrades have been done (sway bar is pretty much mandatory on an 03 due to body roll), I'd say to find out what kind of wear maintenance has been done. While the motor is bulletproof, anything with that kind of mileage on it will use up wear parts like:
- skid bushings (ever been done? if so, how many miles ago?)
- front end bushings (as above)
- ski condition
- shocks (when were they replaced or rebuilt?)
- battery (is it original?)
- track (with 20K it's not likely original, so find out when it was replaced)
- jackshaft and drive axel bearings, especially clutch side (need to be greased 1-2 times per year and it's better if you just change them annually)
- regular oil changes?????
Other things that many of us have upgraded on 03's are:
- front springs to 04 or newer
- seat (to either aftermarket or apex/attack style)
- bar riser
- studs
- aftermarket ski
Hope this helps. WB.