Call up your local college, or art and design colleges that may not be local. Get the name of one of the 100 level professors and have them forward your request onto the students. Students are cheap, and often the professors know which students have a good talent and work ethic.
Alternately, decide where you're going to flyer, and check out the flyers already going in that distribution channel (bus stops, light poles, etc). Find a few flyers that are decent, contact whoever posted them and ask who they used.
Lastly, Craig's list it or use some other local willing-to-buy listing service.