When resources are limited, people often put up letter – or poster-size fliers without prior authorization. Instructors and/or organizers might either do this themselves or hire people to do it for them. Implementing such a campaign involves creating a simple mockup, making copies of it at a print shop or at home using a computer printer, and then putting them up wherever possible: apartment-building entrances, multi-unit houses, columns, bus stations, free community advertisement boards, paid commercial advertisement boards, fences, trees, etc. Highly-trafficked areas are chosen in order to maximize results. Since advertisements don’t stay up for long in visible places (people will take them down or tape their own advertisements on top of them), the same places have to be papered over multiple times. If you have your own car, you can put fliers up on its windows and the car body itself.
You might recruit a pretty large group if your aim is to paper entire neighbors or even towns with a few thousand fliers. However, you should keep in mind that you might be risking a fine by pursuing such an advertising campaign. You alone are responsible for the consequences of whichever path you choose.
It’s quite effective and perfectly legal to put up such fliers and posters in special personal development centers and schools, esoteric bookstores, and so on. There will be some cost involved, but your advertisement will be on display to a key audience for an agreed-upon period of time.