NCSX has peddled Super Mario computer mice before, but the new Koopa shell USB mice are actually usable, thanks to their sleek, ergonomic, aerodynamic, banana peel-repelling, kart-flipping shape.
It also comes with a mouse pad with a gimmick that only makes sense if you place the mouse on Mario or Luigi’s hands. Although judging from how cheap the mice are, I think you might need the mouse pad for traction anyhow. You can order the Koopa shell USB mouse from NCSX for about $31 (USD). It comes in red and green. Because a blue shell would destroy you and anyone you ever loved.