Re: Price's LMB flies
Schlappen is the very webby hackle found around the base of the tail of a rooster. Used often as a substitute for heron or blue eared pheasant in a variety of salmon flies...and obviously some bass flies. Saddle hackle is decidedly different from schlappen; don't know if it would work for you in this application. No harm in trying, I'd say.
If I were you, I'd just google that braid and I'm sure you'll find a zillion places to buy it.