I'm home schooling, too, and I've been doing achievement testing like mad to try to gauge where my DS is right now. It's our first year of HSing, and I'm nervous about gaps in his education.
But if you don't need scores for some specific purpose and you just want a general idea of what your child knows and doesn't know (or can and can't do), then there are many free tests available online. It seems like the higher the grade level at which the child is operating, the more likely it is that you'll have to pay something. But if you don't need *THE* current SAT (or whatever test), but only *AN* SAT from some year, then you can generally save money by checking online and in bookstores.
IQ and achievement tests can be expensive. I'd recommend that unless you really MUST have a formal test administered, you can probably save your money and find a freebie/cheapie.
