When is the factory unlocked iPhone 5 coming out?

When and how much will it cost? And should I buy it or get the galaxy s3?

Basically there's no need to wait for anything as you can simply turn any locked iPhone into a factory unlocked one by getting it factory unlocked either directly from the carrier (if you meet their eligibility criteria) or from one of the big online vendors like http://www.cellfservices.com/ or at a random phone repair shop.