Storing seeds is becoming an almost essential practice in this world where Monsanto and other giants have bought up somewhere around 70% of all the seed companies worldwide. This is important because in order to promote biodiversity, we need more variety rather than less and often the most nutritious varieties are not the prettiest and thus not the most widely available. A friend of mine recently reminded me of a great book by Susanne Ashworth called Seed to Seed that teaches us the best ways to preserve seeds.
As far as where to buy our seeds from, here are a few of my recommendations; http://www.territorialseed.com/, http://www.highmowingseeds.com/, http://www.survivalistseeds.com/ and http://rareseeds.com/. There are other seed suppliers out there but these are ones I know and have used.