I bought my bike for 60 at a pawn shop. I bought it with the intention of fixing it up myself. The bike itself is is an el-cheapo from walmart. It needed new cables and derailleur adjustments right off the bat. So far I have added new shifters, brakes, cables and a 450w 24v power kit to help me with the numerous hills in this area. (Where I live, in Dayton OH, the city is at the confluence of five rivers. So everything is uphill from downtown) Other than the power kit, I've yet to spend over $200 for the bike. Personally, I'll trust names like Huffy, Schwinn and Shimano, that have been around forever, building thousands of bikes a year over some tiny operation cooking carbon fiber on a gas grill that turns out 20 bikes a year. Huffy and Schwinn are still in business because they make darned good products at reasonable prices.

I do admit though that I am of the crowd that believes if you can't take it apart and fix it yourself, you shouldn't be riding it without supervision. I was the same way about my motorcycles. But then I'm a "handy guy" and always have been. For those who are not that familiar with working on bikes, there is a lot of useful information here