My dad is handing down his 1984 (i think) Trek 520. It's still in pretty good working condition with all the original parts. I'm planning on cleaning it up and using it as my daily commuter. The only problem is that he's about 4-5 inches shorter than I am and the frame is too short. I figure my options are to find a longer seat post and a ridiculously high stem, or find a taller frame.

Are Trek 520 frames hard to come by? Anyone know what they tend to run price wise? I know that kind of thing varies by area, so what do you think one would run in your area?

I'd really like to keep this a complete vintage bike, you guys have my gratitude for any help or advice you can come up with.

EDIT: Alternately, how much do you think I could bring in if I wanted to sell it after cleaning it up?