catman pretty much nailed it. Co-op or any farm store have good selections in season and usually have left over seed at the end of the season, just don't expect to see the seeds you wanted on the shelves late though.|
I have planted seeds that have been in the freezer for many years and they have done well. You can also store seeds in the seed pack and kept dry for several seasons and expect them to sprout.
"It is not through knowledge, but through experience of the world that we are brought into relation with it."