I was lucky to find two unopened bottle of H331 at an estate sale, along with an opened bottle, for $5 each. I bought all three, along with some brass, then dumped the opened bottle on a weedy spot in my flower bed and lit it off, very satisfying flash and smoke, well worth the $5 it cost me. I'm sure the powder in the bottle was H331, but I won't trust it.
Saw some powder bid up to over $20 a pound at an estate auction this spring. Add 14% fee to that, and sales tax, they were still saving money.