I sold my q-towers and crossbars to a buddy last week for $50 *d'oh*
They're pretty common though, I'll bet you'll find some in the classifieds sooner or later. The q-towers are a universal fit, then you buy a set of clips/pads that are shaped to work with your vehicle. I had my rack on my old Altima before moving it to my old Legacy - just had to buy new clips/pads.
Otherwise, there are online retailers, like http://www.rackattack.com/