What was stressful about the SAT? IQ testing should be a very different experience than SAT testing. It is one on one not in a big group like with the SAT. Testers are typically psychologists who have quite a lot of experience with creating conditions that will lower test anxiety. Many people find IQ testing to be enjoyable as it focuses on puzzles and problem solving.
I'm unclear - it seems like you are saying in your first post that finances aren't a problem, but in your second post that they are.
The purpose of IQ testing is not just to get a number, but instead to better understand a student's strengths and weaknesses and gain information into how the student learns.