If you're in need of a cheap second-hand bike in Munich, you can just head down to the Munich City Fundbüro at Oetztaler Straße 19 on Monday August 18th. There will be an auction of bicycles that have not been claimed by their respective owners. Apparently viewing takes place between 8:30am-9am only. The auction starts at 9am sharp.
Good luck!
Here is the link in German:
http://www.muenchen.de/Rathaus/kvr/ordnung...5137/index.html