It depends on what's being tested. It seems like you may be looking for a potential 2E diagnosis, which would include IQ testing. Do you have an idea about what kind of 2E your child has? Or would you need broad testing?

Also, the school district should provide this service for free.

We live in the SF Bay area, and IQ testing cost only $550. We went to a highly recommended woman with a solo practice. I think the larger practices charge a lot more. You might want to look for someone who works alone.

Here's a list of people who do asssessments.