Powder with an unknown history is as good as a day-old pile of dog poop.
It could be factory-fresh.
It could be marginal.
Or, it could be something totally different than what's on the label, and dangerous to mess with.
Value is $0.
If you're buying for the container, to use as a decoration, then you have to fight collectors.
The last half dozen pounds of old powder that I ended up with were bundled with some other reloading items at an auction. Had it not been for the additional tools, I would not have been bidding. No one wanted the actual powder. But, because I was fighting collectors that wanted pristine powder canisters, I had to pay a bit more for the tools than I felt I should have.
They figured about $10 per can was reasonable ($50).
I figured $30 for the tools was a good deal.
To get what I wanted, I had to pay more than what they wanted. Still a decent deal ... just not as good as I'd hoped (and none of the collectors hung around long enough for me to sell them the canisters and get some money back
).
Almost 10 years ago, I was given an old can of Unique that had been opened.
It looked right.
It smelled right.
The can looked right.
But I wasn't going to trust it. I like my hands and face the way they are.
The next time I went camping, that "Unique" (if it really was Unique) got sprinkled over the campfire.