Bernie,
I'm in the Plymouth area... here's a suggestion: I was also looking for somebody to blast some parts that I was going to have powder coated. The powder coaters recommended the guy that they send all their parts to twice a week on a regular schedule. I just dropped my frame off at the coaters (I was going to have it coated anyways), and they got it back in a couple days and powder coated it for me. I had no luck looking in the phonebook, etc. So, my advice would be to find a powder coater near you, and give 'em a call. They don't need to know if you don't plan to use them to powder coat, and might have a name or two of blasters in the area.
Good luck!
-Pat-