You qualify for a free academic account (core features) if you are affiliated with an academic institution. You get free credits for the Pro features as well. For Pro feature pricing once you have used all your credits, check out our pricing section https://www.turkprime.com/Home/Pricing.
If your login name is an email address for a edu domain you will auto-qualify for the academic discount. If you are an academic from a different domain or an international user you can request academic stsats here: https://www.turkprime.com/Account/AcademicStatus
Please note that while all TurkPrime fees for using the TurkPrime.com site and its basic features are free, you will need to fund your Mechanical Turk account so that you can pay your Workers and Amazon MTurk for any of their related fees. Also, surveys that are run through TurkPrime Labs or TurkPrime Panels are not free.