I too was in the market for a holster for both my 6 inch GP100 and my super Redhawk. I wanted something in nylon for longevity's sake, preferably a bandolier style, and not something that looked like it would fall apart after 2 years use. None of the stuff at any of the major retailers really fit the bill for me and then I stumbled upon these guys, they don't seem to be very widespread. I ordered a pair online and they have yet to arrive, but they at least look nice in the pictures. The one I ordered was their "Alaskan" model, if I end up happy with it I'm thinking about one of their holsters for my P90.
http://crossfiregear.com/2011catalog/pageflip.html