Guerrilla marketing, as described by Jay Conrad Levinson in his popular 1982 book Guerrilla Marketing, is an unconventional way of performing promotional activities on a very low budget.
If you are trying to reach people who ride, there is no better place to do it than the places they park their bikes. There are certainly others printers, but Contagious Graphics can produce outdoor vinyl stickers with permanent adhesive that won't fade for 3-5 years in direct sun. For $25 you can permanently flyer 250 bike racks street posts and the like around town.
Since you will probably have contact information on the sticker, you may want to consult some property owners before you do this -- or else they may contact you!
A 4.25" x 1.38" also works great on top tubes.
Here is an example used in a similar fashion for the Salt Lake City Critical Mass
- craigslist periodically post [for free] that you accept donations and describe what programs you are offering.
- MySpace is all about community and so are you -- what a match!
- Blogs can be a great one if you can figure out which ones reach the most people.
The key with posters is:
(1) What do they say (2) Where do you put them
Consider the other places that your collective and cooperative regulars hang out, and put posters there. Then consider new demographics you would like to hit, where they hang out, and put posters there too.
Public Service Announcements (PSA)
Your local Community Radio station probably offers free recording and PSA air time for non-profit. Take advantage of this.
Door knob flyers
Take advantage of local Eagle Scout Projects and have them do bike drives for you. But instead of letting them create their own flyer, provide them with one. Here is an example from the Salt Lake City Bicycle Collective that acts as a door hanger flyer for bike drives, but also utilizes the back as a way to advertise about programs. The average bike drive seems to distribute around 200 flyers -- that is 200 houses that just learned about your collective or cooperative!
Build bridges, don't burn them especially when it comes to your local retail bike store. They can be an incredible referral as well as a great place to put your flyers and posters.