the only way your going to find a baja for 12-13k is buying a non turbo one.
cheapest ive ever seen a turbo one, is 15k and that was mine. most sell for 17-20k.
the Vf39 came in the 04-06 STi's. the VF34 came in the 07 STi's. if you can get your hands on a vf34, thats the one to have. but they are really expensive and hard to find. the 39 will serve you just fine. im not sure what they put on the 08 sti's.