We have a collection of small containers we use for pudding snacks, or the kids put their crackers in, or my husband takes to work with salsa, or ketchup and mustard for hotdogs. We get a lot of use out of our little containers. You can find these little containers at Wal-mart for a couple of dollars for a pack of eight.
We use a Quart Jar and dump the mix and milk in, screw the lid on tight and take turns shaking for 2 min (the kids enjoy that part). Then we pour it into our cups and throw them in the fridge.
Instant pudding mix can be found regularly priced under $.80 (store brand stuff), but they also go on sale for cheaper and you can buy in bulk for cheaper. Each of the large boxes can make six 1/2 cup servings. Add 3 cups of milk at about $.38 (for $2 per gallon milk) for a grand total of $1.18 for six pudding cups. Compare that to $2.50 for a 6-pack of name brand pre-made stuff at Wal-mart.
It really does save a lot of money to make your own, and I only spent about 5 min. preparing.