Try salida gun shop in Salida, CO. They are a good, family owned shop that has not jacked their prices. They notify me (and anyone else who subscribes) a couple of weeks before they get powder in, with type and quantity so you can preorder.
Putting one on to save your hearing is a valid reason--especially with some of rifles I hear about here, but I'm a weatherby guy and I don't want to destroy the beauty of the rifle by making it look like a WWII anti-tank gun. Same reason I waited so long to get a muzzle brake-- until I found one...
Why not a 340 weatherby? I drive tacks with mine out to 600 (my personal limit), and it crushes everything I shoot with it--a factory rifle no less with no modifications, using Swift SC II 210g w/ 89 g of H4831 and CCI primers-- but the rifle isn't picky. You can buy that off the shelf for...