My bike of the cheapest and worst quality is probably this 1970 Gazelle Tour del l'Avenir. The current condition is abysmal and I don't know how much of that is due to lack of care or it wasn't much to begin with. I'm pretty sure the seat-stay that is separated from the lug wasn't brazed well in the first place, there is too much Delrin in the drivetrain, the wheels are mismatched and I would imagine this was the bottom of the barrel for Gazelle's offerings. I had to get it as part of a packaged deal to get a Bridgestone mixte for my wife that I wanted.

Putting money into it will be as good of an investment as spending money on liquor and prostitutes but I still imagine I will try to make it ridable at some point.