Due to the fact that they do not do well in warm climates, yak are mostly found in mountainous parts of the USA right now. There are only about 4000 yaks here at this time, and they're mostly found in CO, MO, ID, UT and MN. We have the second yak herd in MI, and there is one in Vermont, as well as one in Wisconsin. There are several in Canada, as well, but I'm not sure what part. Trade restrictions make it impossible to bring more in from Tibet (where they are originally from).
If you either google 'yak for sale' or go to IYAK.org, you'll find some listings. I would advise you against it, though, if your place is in Georgia. They're absolutely hardy and amazingly resilient with about anything except heat. We had a few days here in MI over the Summer when I was pretty worried. They survived, but they were not happy about it. They learned very quickly to hang out under trees near the creek. The perfect climate for them is lots of snow, hills (preferably mountains), with trees and a natural water source.