Well I know someone who went the powerlogix route -- I think it was that one - but ended up buying a cube off of ebay. Said it wasn't worth all the hassle, but perhaps the situation varies.
I like the cube, but I never saw the amazement that others have.
My dad won a contest for them, they sent him a free aluminum PL cube case, it was alright. We both thought that Apple's design was amazing, so why use some third party aluminum one? I mean, yeah, it was cool and all. But I wouldn't use that over a Cube. If you're looking for a Cube case, maybe, you can find one that someone used a PL case and ditched the old one. Good luck, man.