I'm in the market for a touring bike. I had my heart set on a Surly Long Haul Trucker with 26 inch wheels (I have a slight preference for 26 inch wheels for touring) but I have the opportunity to buy a Trek 520 which, based on the color scheme and parts, dates from 1992-94. I have not inspected the bike yet but based on pics, the bike looks clean and well looked after. The owner wants $500 but I think that's too high since I plan on replacing all the parts I am not certain of before doing any serious touring. The bike is also a 7 speed which is not a deal killer but it will only get harder to find parts as time goes on. How much is the darn thing worth?