Someone left behind an early 2000s Mongoose full suspension mountain bike at our house. I recently fixed it up for a friend of mine. It needed new cables and a set of used aluminum front brake levels. The original front brake levers felt like they were going to snap off and twisted like crazy when you clamped down on them. With all parts and stuff, I put about 20 dollars into the bike. That doesn't cover my labor costs at all. I spent about 2-3 hours total redoing the whole bike with all new cables (brake and shifter) and major cleanup and tuneup. I gave it to my friend for nothing more than the cost of the parts I put into it.

If a shop were to charge say only 40 dollars an hour, that would be 120 plus the cost of parts so a total of 140. And that is a very conservative estimate. All that for a bike that is worth 50-75 dollars tops on CL since it is a crappy Mongoose.

I can totally see why a LBS would not want to invest a good amount of time into a crappy walmart bike. Throwing good money after bad big time.