They are not cheap, do a search on the board for Gyration.
Website
in the UK about £100 with mouse
try ebay
http://cgi.ebay.co.uk/ws/eBayISAPI.d...sPageName=WDVW
http://cgi.ebay.co.uk/ws/eBayISAPI.d...sPageName=WD2V
Note: there is a long range one and a shorter range one. The shorter range on is fine for in the car.