If you look through the other posts here, you will see that the first bit of advice is to get fitted. The Trek that you are looking at will fit you only if you have a 30" - 32.5" inseam. A bike that does not fit correctly will normally be very uncomfortable to ride for any appreciable distance. Unless the fit is off by a large amount, the bike will feel OK for a test spin around the block, but when you have been at it for a couple of miles, the ride would be unbearable. If you continue to ride an improperly fitted bike, you can cause permanent damage to your knees and back.
This website can help you determine your fit, but unless you know what you are doing, I suggest that you go to your local bike shop and have them fit you. There is a charge for that service, but it is better than buying a bike that is useless.
http://veloweb.ca/bike-fit/
But to answer your question about the bike, it is around a 1987 or 1988 bike. It looks pretty in the picture, but a photograph won't tell you much about the bike. The brakes are single pivot side pull brakes, so the first upgrade that I would make would be to get the brakes replaced with dual pivot brakes. Single Pivot brakes have to be re-centered frequently while dual pivot brakes pretty much stay centered once they have been set and have much more stopping power than single pivot brakes. Dual pivot brakes also apply more even pressure on the rims so that the braking action is more balanced and predictable..
I think the price of that bike is a little high to begin with, considering it is over 20 years old. Without knowing the condition of the bike's components, it is impossible to try to place a figure on it. If it needs a new freewheel, chain, and chainrings, you would be spending nearly half of what you paid for the bike to get them replaced, providing a 7 cog freewheel can even be sourced.
