The last two times I went to order BEP the supplier was out - no back orders. BEP must be under pressure for some reason. I like the Mallard solution but the whole problem raises the question of whether getting into dying feathers is a reasonable alternative. I don't know of anyone that does it routinely but I have heard it extolled as the entry way to a whole new world of tying.
The other thing that I have experimented with a little bit of success is steaming feathers for winding spey style patterns. Probably a cheap alternative to some other approaches but I haven't used the flies tied extensively - no feedback on durability.