Waiting for sales?
When the next sale comes on for a stuff pack, report it in this thread! A lot of players, me included, buy stuff packs during sales because it seems to be more worth the price. Right now, I'm wait...
Forum Discussion
Your best chance for Stuff Packs to go on Sale will be the Big Summer Sale. Not sure when the exact dates of the but it's usually after the big Steam Summer Sale. I believe they do sometimes go on sale again later in the year but it's at most once or twice a year.
