When I was at home for a week earlier this summer, I talked to someone about them, and they mentioned that there's a selection for sale every Thursday afternoon in front of the Art House café on Ingersoll, if those of you in Des Moines want a venue for trying them. I know the Art House promotes them, since last year my parents went to a dinner there featuring all courses with heritage tomatoes. Alas, my trip was short enough I never made it down there to buy any when I could.
Cronaca recently posted on the subject in Britain, where it is generally illegal to sell heritage fruits and veggies because the breeds are not stable, nor registered with the government for a fee of 1000 pounds, a bit much for a local grower. The seeds are not illegal to give away, and they can be legally grown in Britain, but lack of ability to legally sell them does put a major damper on the market. The article that Cronaca cites is here.