LUk (a German firm and GM OE) makes a Gold Pro Series. Lingenfelter used to sell these at around $700~, supposedly good for 700 ft/lbs. Rock Auto has them for $350~, that includes the FW, etc. Far as I can tell this would be an LS7 or LS7+ setup.
http://www.rockauto.com/catalog/more...798&cc=1361450
RA also has an Exedy setup for $450, but I can't find any reason it's better than the Luk except maybe in the disc material/design. But not clear specs.
I'm going to get a clutch before going to the machine shop since may was well get it balanced while it's apart. It's only $125 and may make a nice difference for overall smoothness on longevity.