I tried facebook ads and had little success. The click to conversation ratio was terrible, I was better off using search engine ppc.
luckily I had $400 in free credits to use so it didn't cost me a thing. Im not sure if these codes work anymore but you can get $350 worth of free advertising on facebook.
Details found here
http://www.searchenginepromos.com/fr...rtising-money/
I know you can at least get $100 free.