Petco gets them in from time to time.
If the banana bits rot off, just bury the stem-head into the substrate so the leaves come up.
Propagation by sucker off the running roots or by lily-pad drift.
From what I've read these will grow another banana structure under the lily pad they send up. I've had two send up lily pads in a 5 gallon tank and one of the stems went all the way down the tank and came back up. Was wrapped around the filter and the heater and grew about 3 inches in diameter before the leaf died and the plant went into shock and dropped all its leaves. It's growing again now.
They are quite cute plants but they don't like having their leaves roughed up, they will wilt and drop them for any damage at all.