I'd say no to the 30 gal...first, you need a 7" sandbed, so that's likely close to half the height of your tank, secondly, you'll want to set up an alternating back and forth flow pattern (hard to do in a smaller setup), and finally, IF you can get them eating, they require a lot of food in the water column which is pretty hard on the water quality.
I've considered keeping a couple in a 60 gal, but I'm thinking even that may be too small to do it right, even if I design the tank around them. Besides, one or two specimens isn't NEARLY as impressive as a group of them.