Hi:
DJs don't spend a lot to market themselves - which relegates them to a heavy and consistent presence on social networking sites like Facebook and MySpace. If I were you I'd create accounts on both sites for your company, and then start inviting friends using "DJ" or "nightclub" as search criteria. I would also spend a little money on Facebook ads (maybe $50 per week) targeted to the market(s), zip codes, etc. you want to reach. Lastly, I'd hit the street with business cards and an opening offer or clear point of difference (i.e. you are less expensive than Guitar Center, your gear has the best warrantee, etc.) and go to clubs and meet the DJs. Make them work for you, so to speak, by way of word of mouth. Hope this helps.
Marc-Portugal