You do not want cheap marketing -- period. It's better to have someone do the work pro bono (which is not out of the question given that you are a nonprofit) than to be paying $10/hour for someone to help you launch. If they are cutting their rates for you, they are unlikely to be doing their best work. If they charge $10/hour normally, they are probably not very good marketers. A few other people who have answered this question have suggested college interns; this might be a solution for you but I'm not sure how well-versed they would be in the nonprofit world or the subject matter at hand. I would think it might be better to find a college student who's digitally savvy and passionate about your cause rather than one who happens to be majoring in marketing.

Another option is to consider using a site like VolunteerMatch or Catchafire, which are marketplaces for digital professionals looking to put their skills to nonprofit work.

Alternately, one or two Clarity calls with a nonprofit marketing expert might put you on the right track to handling your marketing yourself. I am happy to take a call if you are interested; I'm a marketer who is on multiple nonprofit boards.

Good luck!