cheap bikes in Japan?

Recently on various news articles I have seen of the mountain of abandoned and confiscated bicycles held in Japan, thousands of them are being sent to poor African areas simply to clear space and dispose of them. Where can one potentially purchase such bicycles cheaply as an alternative to a new bike in store? What is the name of these places, and also the term for the cottage bicycle repairers?

I got my bike at a small bike shop that sells new and used bikes. They also make repairs, mostly tire repairs. They did all the reistration for me.

You can also get free bikes from the city trash, at least in my area. I can have two free items a month. I didn't get my bike there, but got a nice kitchen cart. I was told go early in the morning as the good items are taken early.