I've contacted one of the companies that will ship foam nationwide, but I'd really like to buy locally. Anyone know of companies selling XPS or ISO used in Michigan?

Not what your asking for, but I'd give them a call. 2 inch 4x8 sheets of polyiso $16. 3.75 inch for $27 (large quantities).

http://www.ohioinsulationking.com/

Thanks. I emailed them but never heard back. I might try calling them next week.