This site has been a boon to many:
There are very prominent growth hackers on there who will take your call, give you advice, and steer you in the right direction. Some are pricy (they charge per minute, I believe), so it's best to have very specific, succinct questions already planned out prior to call.
Sean Ellis and many other greats are on there, as well as up-and-coming scrappers who have raw talent are making names for themselves.
Growth hackers (and this term for internet marketers is hotly debated) are hard to find, and the good ones are usually either consulting for venture-backed startups and established firms, or are doing their own thing.
I wish you luck! :)