gmpp@fichtnerchevrolet.com
This is the email for Dennis Fichtner at Fichtner Chevrolet in Montana. Any Vette owners here who have been active on the Corvetteforum.com will know this place is legitmate.
Not sure on prices for Hummers, haven't checked, but a few years ago, they were going to sell me a Vette GMPP at less than I could obtain via a GM employee discount.
Should be worth a try.