The tester that we used is the head of the G/T education department at a local university. She is great with children. She tested him at 4 and now again at 7 and she is wonderful. She is very knowledgeable about gifted children and the many levels. For the 2 test that ds did take it only cost $300 which is very reasonable.
It has been a long time since I have read Dr. Ruf's levels. I know that my son wasn't in the top level but the 2 levels below that he fits in with her description.
Wow - that's very reasonable in price, and it sounds like the tester has a good match for your son and your needs.
Remember that, by my estimation, most Davidson YSP kids, who are all 'profoundly gifted' are level 3 by Ruf's book. So matching the 3rd and 4th levels is a picuture of a very unusually gifted young person. Unusual enough that even schools that are used to 'gifted' kids may be in over their head with a level 3 or 4 kid.
Best Wishes,
Grinity