I really commend them for doing it. It's a commitment I could never make 100%, though. I loathe squash, and that would be just about all I could find during the winter. Plus, I couldn't imagine life without avocados.
I'm lucky that I live in the heart of farm country, and my city has one of the best (if not the best) farmer's markets in the country. For the majority of the year I could easily live off what is grown within 100 miles of me. However, I can't even imagine trying to do something like this in Phoenix!