My family dressed up as the Mario family this year, and, if I do say so myself, Wario was the coolest.

This costume is fairly cheaply made, but looks ok, lasted me through Halloween and is probably good for another costume party or two down the road.  It comes with a foam hat, a nylon combination purple overall/yellow shirt, two oversized white gloves, an inflatable mushroom-belly and a stick-on zig-zag mustache.  (IMHO, you could get a better effect doing the mustache with face paint, but I was lazy, so I used the mustache.)

Highly recommended -- as I said, it looks a little basic, but it made our night.