I've seen them around, but can't think specifically where I've seen them. Not sure where you are, but maybe try Pierson's in CR...they do a lot of tropical house plants. If you want to mailorder, a Google search brings up lots of hits.

They were available at Wayside Gardens. If you don't see them there. A toll free customer service number is there and they are very nice, helpful people. Give them a call. ;-)

Here is a link that might be useful: Wayside Gardens