Contact your local board of education...
Hello Doc,
It is my guess that your local board of education would be the best and only place to start when it comes to this subject. Home schooled children have to be able to pass the same tests that their publicly educated peers must pass.
Also I have found several web sites that offer such tests, most were for a fee and some were not. Why not try a broad Google search using the terms standardized testing for gradeschool children or even a search using the terms home schooling. The Internet will bring you much information if you just look for it.
Amy :)