i've seen these tanks at the new york aquarium when they were setting up their jelly exhibit...its not out ragiously hard to make one if your good with tools
Kreisel's are pretty kewl things - they aren't easy to make and would recommend getting one professionally made and shipped if you are considering
Moon jellies are the most common to keep, live the longest in captivity and eat more readily - most aquariums keep these.
Check these guys out - we priced out an installation at a restaurant (17 large) and thought it was pretty cool - they will also be at MACNA this year in Pittsburg.