I got a great bike on eBay, a 2000 Specialized Rockhopper for less than $250 including shipping and it's served me extremely well on a dozen trips, well over 200 miles, in the last couple of months with only minor maintenance required. You can search eBay or craigslist for some good used bikes...
Waste of time. A bike is a tool, not a piece of art. If you want to preserve it, then don't ride it, just display it on your front lawn every Saturday and stand next to it looking awesome (posing = poseur). If you want to ride, then you're going to fall, crash and thrash it.