I am a data scientist/statistics consultant, and have consulted to a few startups and one soft drink company that is often confused with a drug.
Can't say for their experience, but I can say why they hired me: make sense of data. Fact is, most "big data" out there are mostly junk and useless. Being able to pick out the ones that work is actually most of my job description.
Where? One of which are on HN, two are from hackathons I attended. Another one actually came from a friend of a friend.
How much it cost? I charge per hour, and ranges from $80 - 300 per hour.
Hire me again? Everyone so far is a repeat customer.
What I'm thinking of doing? Hanging up the jacket. Consulting is a tough business.