I think that is a great price, too. Especially since she already has all her puppy shots and will be spayed and have her baby teeth removed when you get her. You will have no costs other than feeding her and her annual vet checkups. And since she is 6 months old, you know exactly what you are getting as far as size. No surprises. I say GO FOR IT!
I paid $900 for both of mine, but I had hundreds and hundreds of dollars in vet bills due to checkups, puppy shots, spaying/neutering, ect. ect. ect. So, $1200 is a great price!