It's been three years since I flew out of PGA, but I don't remember any rentals when I was there. Someone else suggested contacting Classic, and I would second that. They were a helo operator when I was there, but they should have the best info.
I would also suggest that you contact the FBO's at Flagstaff. The route from Flag to Page takes you over the painted desert, and a short detour takes you over the eastern end of the Canyon.
Also, check into some of the small airports in southern Utah.
Finally, you didn't mention any experience in the area (if your familiar forgive me), so let me say that you really need to make sure you take den/alt into account as you fly. Flag is over 7000 feet and even though Page is only around 3000, it can still get hairy. The airport that is halfway up the lake (bullfrog, if I remember) is pretty tall and you can easily get into trouble.
If you are able to make this happen, make sure you take a look at the Rainbow Bridge. It's at the NW base of the big mountain. Just don't try to fly under it.
have fun