I do as of this month. We had our testing done on December 2 and here in Ohio, the cost was $50 for the year. It's $30 for the year if you have less then 30 birds, but well, I have considerably more than 30, so it was $50.
My paperwork with my NPIP number arrived on Christmas Eve!
As far as I know, it is free for Illinois but there are only two private certified NPIP testers. Not sure of any other costs for the supplies they need or who pay for their supplies. I am still waiting on a call from one of the testers but so far, nothing.