I have just recently found two independent ultrasound centers who are happy to see my clients for cash payments of somewhere in the neighborhood of $100-$200. One of them is in Jackson, which is about 90 minutes from Grand Rapids.
I would recommend doing a yellow pages search to see if there are independent ultrasound centers and then calling around to see if they would see you without the referral of a licensed provider. Some of them will, I would guess, but they might not be willing to submit to insurance and you might have to pay cash.
Stacia -- intrepid mama, midwife, and doula. Changing the world one 'zine at a time.