www.bikeisland.com

They sell the Gigantex sourced rims in 50mm tubular and clincher sets. I have a tubular set, bought here as part of the bikeforums group buy a couple of years ago. They have been super reliable so far; I've raced and trained on them extensively, have thousands of miles on them, and have yet to even true either one. I recently weighed my set at 1540 grams.

If you want a nicer set of hubs and handbuilt wheels, contact psimet at psimet.com; he also uses the Gigantex rims and can build pretty much whatever you want.