As global warming takes hold, bio diversity may be the only thing standing between full bellies and starvation. Listen to this TED Talk about seed saving and bio diversity. Take a look at the Svalbard Global Seed Vault here.
My opinion is, if you can't save seeds and need to buy some, get a good supplier. I like Stokes. They are an excellent quality seed company and their seeds always seem to take.
When you buy seeds that turn out to be duds, most likely that's because they are old or were not stored correctly. Harvesting and storing your own is the solution.
Once your veggies and plants go to seed, if you don't collect some for next year's plantings, you are wasting a valuable resource.
I keep my seeds in paper mailing envelopes, and label each accordingly.
These photos are part of my growing collection from just this season.
So far I have collected, romaine, mustard, brandywine tomatoes, mesclun, rhubarb, garlic, poppy, cucumber, fennel and a single apple seed from a neighbor's rare apple tree that's on its way to extinction.
The majority of apples on that tree had no seeds at all. It took dozens and dozens of apples to find just one seed. I'm going to plant it and try to nurse it to life. Those apples made the best darned pie I have ever tasted.