I'm part of a group that does the same thing, but in NJ so we have a greater population to use. What we do is to have bike drives. We have drop off points at all of the local bike shops. We also sponsor corporate bike drives. What you can do is to ask local churches and scout troops to run bike drives every 6 months or so. This is a great service project for the scouts, they should jump on it.
Good Luck.