I've purchased many of my plants from the two sources that Mike suggested. I haven't tried seeding bananas yet. I guess I am too impatient. It's hard enough to wait for a year or two (or more) to see plants flower.
We've had the terrible heat here as well. It was 110 on Saturday with thunderstorms. The bananas actually seemed to thrive with those storm conditions. Well, until a very strong wind came through and did some leaf damage.
Mike, I'm going to try that sheet composting in my garden area this winter.