I bought three 'big box' store type racks i found at a local 'Crazy Eddie' sort of place. They are square tubed and nice. i filled all the tubes with sand, sealed them up, and have a nice tall rack. and two low ones, One for the Video and Plasma, and the second for two TTs and stuff.
They cost me $150 each, then the work of adding the sand.
I have used them 6 years now and am very happy with them.
They do have tempered glass shelves, held in clamps, but I use rubber footers, and no vibration problems.
They are not the usual mass market design, and I can't find them anywhere anymore, but I am certain others ar out there that would be great.
Just keep looking.