Actually, I have found many highrez photos. The trick I found was to do a Google search on the celeb that you want and then click on images and then select large only. So, when you click on the image it will take you to the site that host it. Search through those sites, they are full of high rez photos and quite often for many celebs.

Also, if the site wants a you to register, just click on the , "Full size" like beside the image thumbnail. This will at least give you that image without the rest of the hassel.