Thanks for that info Allocator, would there be any risk involved buying second hand box?
I missed the fact that it was a second-hand RB you were thinking of buying. You will need the original CD packaging with the user name and password on it. If you don't have this, it's not a show-stopper as AirNav Support will be able to help if you let them know the serial number of the RB (printed on the label on the underneath of the hardware receiver.)
As Orkney mentioned, RB comes with 12 months free access to the 5-minute delayed shared Network data. If the 12 months is up, them you have the option of just watching aircraft picked up by the antenna at no cost (everything else works, photo download, database auto-populate, weather information etc), or purchasing either the 5-minute delayed Network data, or the real-time data. Prices are shown on the AirNav website here.
http://www.airnavsystems.com/RadarBox/order.html