Looks like it's only preorder starting next month from Paizo. If you're lucky you might find it in a local store, but that really depends on where you are and how popular Pathfinder is there.
It's. Been back-ordered since April. They are printing a second edition. More info here.
I nabbed mine from my local shop this past Christmas. There are still a few to be found out there. Check the local stores if you haven't already.