Buy.com has Microsoft Wireless Mobile Mouse 6000 - MHC-00001 for $35.99 + free shipping.
Worlds most advanced tracking go more places than optical or laser
Features
BlueTrack Technology: Works on virtually any surface
Leave the Nano Transceiver plugged in or stow it in the mouse.
Reliable 2.4 GHz wireless connection and virtually no interference.
Use your mouse without power interruption for up to 10 months.
Work more efficiently with 5 customizable buttons and 4-way scrolling.
3-Year Limited Hardware Warranty
BlueTrack Technology does not work on clear glass or mirrored surfaces.
Limited Warranty and License Agreement available at
Microsoft Hardware Warranty Information.
Microsoft Wireless Mobile Mouse 6000 - MHC-00001 - $35.99 FS 
