I agree the prices for that type of powder sure isn't what it used to be.
But I'm sure you also know that 4064 is at the edge of the gas pressure/over time envelope the M1A will tolerate without the Shuster adjustable gas plug.
Anyway, don't get me wrong; I've loaded a ton of 4064 and also IMR 4895 (or whatever it is) and gotten excellent results. I have no complaint against either powder.
This foray was more just to do it - to duplicate those two cartridges as a "project" than because of any perceived shortcoming in commercial grade powder(s).
I, and I have the feeling like you, simply enjoy the process of load development.
Someone near and very dear to me is about to take delivery of a 450 Bushmaster. And I'm already greatly anticipating the fun I will have working that cartridge up.
We will have to gather at my place for a BIG BORE AR15 DAY/Cook Out. A day filled with .50 Beowulfs, .458 SOCOM's, and .450 Bushmaster's sounds fun... I can hear the steel screaming now...
Signal-0 Productions Firearms Training... for the working man.