I purchased bulk power back about 30 years ago and finished the last of it two years ago. I was doing so much match shooting that I had more than a few dozen empty GOEX cans on hand. I repackaged the bulk powder into the cans. As far as gas cans go. Check and make sure they actually seal. Some cheap gas cans will leak/drip if flipped up side down. That will let humidity in. Some of the specialty hardware/paint stores sell one quart cans, the type that paint thinner comes in. dead ringer in shape for the old GOEX cans.
I am by nature a bit of a pack rat and I keep an assortment of used containers around for those special jobs like this.
For pete's sake, also make sure the containers are clearly labeled. Helped clean out an estate where the old timer stored all kinds of powders in anything and everything. Old medicine bottles, dish detergent bottles, even glass jugs and pickle jars. We did not know what any of it was, except probably smokeless for the most part., so nearly all was just dumped and hosed down the drain into the city sewer system. The guy who was given the task, dumped one container on the wet concrete and it turned out to be carbide. (calcium carbide, I think) That was an experience he won't soon forget. A fire did briefly flash above the drain.
Anyway, enjoy the good deal and be safe.