Storebought, homegrown, and gifted seeds all intermingle in my seed box.  Before ordering for the next year, I always sort through, removing packets that are too old or are filled with varieties I tried and didn't like.  Next, I pull out saved seeds from two years ago and put them in a to-go-soon pile --- these are insurance just in case the ones I saved in 2012 don't turn out quite right.

Meanwhile, I set up a germination test for seeds that might no longer be viable.  I often buy seed packets that hold more than one year's supply if I know I like the variety, but it's worth testing these older seeds to ensure they'll still sprout the next spring.

With all those ducks in a row, my seed bill is always under $100 (and often considerably less) for a vegetable garden large enough to feed us year-round.  I do spend a lot more on straw and cover crop seeds, but we still consider the delicious food a bargain.