A superb wireless mouse - fits my man-size hands properly. It has Darkfield technology which means it works superbly on glass & other reflective surfaces. They are the only ones I have found which work well on my laminate PC desk.
It is a wireless mouse, however it is charged by USB, so does not have to rely on a steady supply of rechargable AA batteries, although it does use one. The mouse can also be used while plugged in to USB (if you don't mind a wired mouse).
I know that some lucky people have gotten this for £20 recently from their local Tesco, but not everyone has one of those nearby.