Replying to myself here to give some info on my experiences with FB:

Here are my stats on the last week for one campaign where I make about $35-$50 on average per lead:

- Spend: $3,345.30 - Impressions: 6,305,765 - Clicks: 2,570 - CTR: 0.0408% (average, some ads are near 0.1% and they make the most money) - Average CPC: $1.30 - Leads: 237 - Average CPL: $14.11 - Revenue: $8,703.70

That's a pretty damn good ROI. Not every campaign does as well as this, but taking the time to find your audience, craft your message and optimize will yield good results.