Welcome!
I don't have any experience obtaining an IQ for my children, as we've never bothered to have them tested. I do, however, have experience getting that number for other people's children.
Ideally, one would like a school, neuro, or clinical psych experienced with GT kiddos to administer a current test. (The WISC-V is now a year old, which means most psychs should have switched over to the -V by now, though small rural districts with limited funding may be trying to eke another budget cycle out of the -IV. Low-volume private psychs may hold off on the newer edition for similar reasons. Specialty GT psychs may wait because they are more familiar with the clinical characteristics of the old test. But everyone really should be moving on to the -V, as norm obsolescence/Flynn effect predicts that scores on the -IV will be unnaturally inflated.) A good evaluation should also include more than a few scores; a skilled clinician ought to provide you with a comprehensive interpretive report describing her learning profile across a number of domains (the specific ones will depend on the assessment instrument(s) used).
$180/hr is not a crazy amount of money for this kind of evaluation. It is not unheard of for a cognitive-only assessment (aka IQ test) to cost in the $500 range, plus or minus, including a testing session that usually lasts about 1-2 hours (depending on how quickly the child works, and how high they go), pre- and possibly post-testing interview/review of testing, and time to write up the eval.
I would say, all other things being equal, that you are probably going to get the most nuanced results from an assessment professional with GT experience.
