Mark, Here is a link to Smitty's
He's got the natural black, White, Grizzly, and Blue Dun. I am taking a class with Jim Casper (sp?) at Smitty's tomorrow night and will pose the question of the neck hackle. The way I understand the construction of the fly you are using a neck hackle over the fan of bucktail as a support mechanism. The neck hackles are much stiffer than the saddles.
Looks like Juro beat me to the punch on the link. I'll add that I scheduled the class some time ago and after seeing Todd Murphy tie flatwings for a few hours I think I've picked up a trick or two. My attention was split between helping the kids tie, greeting the many visitors and trying to take in lesson but you couldn't help but learn something. Todd is a great teacher.
From what I've seen at the shows Saltwater edgie is the place to go if you want to pick from all the colors of the rainbow. The Bear's den also has some nice colors of bucktail and some hackles.