Here's a few places:
Quilt Curio Case, glass front:
http://quiltcurio.tripod.com/id2.html
How about JC Penny (clearance $180, for plain one):
http://www.jcpenney.com/jcp/X6.aspx?...0Quilt%20Chest
check quilt shoppes. A lot of times, I see them built by a local craftsperson. Also, there will almost always be a seller of such things at quilt shows...
good luck!