I'm looking for used bike with 20" wheels and steel frame. I'd like it to be upgradable with components of standard dimensions, because I'm a bike tinkerer and like to make improvements where they make sense.
What models and brands should I consider? State of repair doesn't matter (within a reasonable price range), because I can fix any bike up.
Where is a good place to look?
I haven't decided on a price range yet. Let's start with $200, and I'm open minded to spending more in the near future.