here's my first hand experience. i bought a used one complete for $150 as my first fixie and rode it for a few months. yes, it's built up of mediocre at best parts, but honestly the biggest *problem* i ever had was the ridicule. i'm ~150lbs and i never striipped the cog - i'm actually still riding those hubs, never broke a crank, never bent a rim. would i buy another one? no, now that i know there are better options for less money. should you never ever buy one under any circumstances? i don't think that's the case.