And often the seeds that you get from swaps are better germinators than commercial seed.
I do the NARGS swap every year as they send out Phytosanitary certificates so we can send seeds across the border.
I also am in a Canadian swap.
In the New Year there are Seedy Saturdays held across Canada.
They always have a table where you can drop off excess seeds, and pick up other seeds.
You can also purchase seeds and plants from small seed/plant growers there.