Extrusions are definitely one way to go if you can stand the price. Light weight, attractive versatile. I couldn't stand it so I just used plywood which is probably more versatile but way not as cool.
They've been making those things for a while now, they used to be used at dealers with a festool shop-in-shop for the testcenter.
Quote from a post from Januari 2008: "Prices ar by request, but they have a listed price for the cart, that shows me this system is "not for me". (€ 1750, now on special for € 1495)"
The old links from te post don't work anymore, but if the price was for the version with drawers on both sides it's only 31€ more expensive now (but back than it had metal drawers instead of the plastic ones )