A4Tech NB-57D battery-free wireless optical mouse. These have been around since 2006.
Yeah, battery-free as in no battery required, which solves at least one of the biggest issues with setting the mouse free, or nearly so since the USB mouse pad is a critical part of the magic. It works via a process dubbed "magic magnetism," which is an apparent A4Tech cocktail of electromagnetic induction and RFID technologies bundled into the kit.
The optical mouse delivers an 800DPI sensitivity and features 7-buttons plus a scroll-wheel which can be endlessly mapped to shortcuts via the included 2X-Office software (provided on CD). The mouse features '2XClick button', which enable users to click just one time to operate programs instead of double-clicking, and 'office (program map) button' that can run programs right away without moving a mouse pointer.
The 10g mouse runs on a dedicated mouse pad (22cm diameter) powered by a USB port. By using RF wireless technology, it solves conventional signal interruption problem which often occurs when multiple mice are running in the same area.
$19 plus freight $15 to Qld = $34.00