Yah, they charge a premium for them. It would be nice to have one, but then you are limited to just refills. No exchanges.
I have been casually looking for one one CL and FB MP over the last couple years and had a couple near hits, but they just don't pop up often and if the price is decent, they disappear quick. People seem to know what they have if they have one laying around.
I mainly wanted one for my camper like Bobby. I got tired of dragging a big 20lb tank along for my Q100, so I plumbed in a quick connect tap on my trailer off the main tank.