I would look around for a tester with experience in GT kids. We found one that our insurance accepted. We had to pay for the test itself, but the other meetings were billed through insurance. The total cost for us was around $175 for WiSC-IV
I found the testing very helpful in understand my DS. I agree with Lucounu! Try to stay away from bargin testing if at all possible. I would make sure the tester is experienced in GT kids, extended norms, and GAI.

Good luck