A few years ago I was in a Horrible Freight store and they had all kinds of packs of seeds for 10 cents a pack. I bought several dollars worth and every now and then I run across a pack that I never used.
The last time I tried any of them they were pretty old but I got a pretty good germination rate from them.
I've also bought a ton of post season gardening seeds ect. from Dollar General.
The only thing with DG is stuff don't last long when they put it up for close out.
i always ask at the hardware stores if they have any old seeds on sale later in the season. one year i picked up a whole basket for $2, must have been 50 packages of seeds in there. most i never used and eventually i took them out back and scattered them around. only the fennel, beets and leaf lettuces i used the next year and it was fun. in the place i scattered them i had a few things actually try to grow but the bunnies, etc. got most of it. only the dill and a few lettuces. the lettuces i don't think had a chance and never flowered. the dill did great. i'm curious how much of it i'll see this season when i get back over there to look.