The dealers with the largest and most varied selections that I've had good luck with, Smoky Mountain Knife Works, Knifeworks, Grand Prairie (GP), New Graham...
Check out AG Russell too - not the largest selection, but his own brand products are excellent and are often bargains.
For more niche-market shopping there's Sooner State, Collector Knives, Deadwood Knives, Old Hundred Collectibles, Ragweed Forge...
I recommend all of these based on personal experience. :thumbup: