I just bought a pair two weeks ago from Kaufmans in Seattle. http://www.kman.com/Catalog/Page050/Page050.htm
They were actually less than most Internet prices ($330 vs. $375). At those prices and expected life of these waders (Simms) - I think it's extremely important to try them on. I thought I was a medium. Turns out the small/king fit much better. Also, I tried on matching boots and liked the Patagonia Beefy best (I have wide feet). They were real patient as I tried on several different combinations. In the end, they even threw in some chum flies I was going to purchase. If you can't make it over here, you might call them and see what they suggest.