I also only buy powders in 8lb jugs during non-shirtage times. Never buy 1lb when there's and 8lb on the shelf. Especially pisto powder. An 8lb jug is over 10k rounds.
Back when I was reloading on the reg I bought them all... because those 4 x 1 pounders you turned down in powder X, a few weeks might go by and then its just gone. Bigger is better when available, though. Even when the market is flush, some powders come and go from the market in waves. Like for awhile stuff like Titegroup and Unique would disappear for long periods.