They are around, but a little hard to find right now. They do well for us here in Florida. As I understand, in the not too distant future they may become much more available. Will let you know when I know.
Yes, I've chatted with many people in the past about this plant, Jeff most notably and Mike Catalani. It is a true lowland, seemed to do best for me if it was around 70F at night and at least 90 in the day, but probably would have prefered it much more hotter. I've heard that they grow in very wet conditions in the wild as well.
A friend of ours grew a beautiful specimen of mad. in sweltering humidity and heat. Nights were more like 78 F. during the summer, but it did not object to winter night drops down to 58 F. Grows it in pure lfs. It finally reached the top of the greenhouse and flowered (female). I believe he chopped up the vine once the ground shoots started, and threw it away! (not the plant, the old vine)