I was going to say that (the buy the 120 from CC, use the $40 off coupon and get a free car kit). That slickdeals thread stole that very idea I posted previously in a different thread (on slickdeals).
Otherwise, since the new Zunes just came out, I don't see them really dropping in price/going on sale too much of late.
I know that the $40 off coupon works on the 80 GB model (I bought this one because I wanted the red one).