Ultralight, this is the only page i've marked about the test scores
http://www.hoagiesgifted.org/highly_profoundly.htm
Which at least gives you the common ages for the tests.
I only remember the DAS because I think it was much cheaper than the others.
Speaking of cheap, I've read that if the IQ score is really close and you have a qualifying achievement (free at school, right?) that they will take a portfolio sample of work that's a few years ahead of grade and count it as close enough.
This thread says how Aimee Yermish once said to test a mathy kid(poster here who's also a professional gifted psychologist).
http://giftedissues.davidsongifted.org/BB/ubbthreads.php/topics/89101/Best_test_for_math_talent.html

Youth lives by personality, age lives by calculation. -- Aristotle on a calendar