I like the ones Kings River Quilt Guild, Dinuba, Ca., made. Theyre from PVC pipe of varying sizes. Uprights are 4" in 2 & 4' sections connected with T's so they can be made any height. The cross bars are attached at the T's. There are holes drilled in the uprights every 4" that long S hooks are put into to lay more cross bars across. They're layed out like a rale fence /\/\/\/\ . So they can stand without feet that people tend to trip over. They use wood mallets covered with a soft fabric to assemble them.
As their show has grown, they have made more. I think the initial cost was ~$2000.