Myosith, that is a good idea for buying used bikes. When I was bike shopping in Minneapolis I found a number of small business guys who would get used bikes, fix them up, and sell them. Some just did Craigslist but others had actual shops. Maybe your area has folks that do the same. I looked at some of the bikes, they had some great choices, just none that worked for me.
My husband last spring bought a low end Trek Navigator new from a bike shop for half price as it was a prior year model. That is also something to look for.