It's my understanding you're legally entitled to free testing through the public schools under federal law. You may have to put such a request in writing and may have to go through the special needs department. In some states, homeschoolers are legally entitled to annual testing too.
With our local public school system, I've managed to request having the Woodcock Johnson III Academic Achievement test be administered to my 2e/pg ds8. DYS accepts this test; of course, you'll need to get a qualifying score for DYS. But at least you won't have to shell out money for the test if the public school administers it.
WJ-III isn't an IQ test, but it will give you information on what level your child is reading, writing, and doing math - provided he cooperates and works to his true ability.
My public school system was willing to test my son when he was 5.5 yrs old and still in kindergarten at a private gifted school. I said that I was considering the public school (no, not really, but didn't say that) but wanted him tested first to think about what school I would place him in (we have school choice here).
FYI - DYS requires ONE qualifying score AND a portfolio. I submitted ds's portfolio in June and DYS accepted them. However, ds blew off the WJ-III test from the public schools (was using his fingers to subtract) and therefore didn't get a qualifying score and didn't get accepted as a result.
