Biggles,
has the figure quiet close actually. Depending what kind of SBB equipment you want to put in, STC, work hours etc. Also you'd want to know if you're getting a basic setup or one with acceleration. IF speed isn't a priority you're good to go with any of the following...
Thrane & Thrane
Colllins - Via the CES /Router or CNX router
HW - Same thing, CES/Router or CNX router
Aircell are now in the market as well.
Mind you - SBB, can be an expensive monthly if not monitored correctly. Swift 64 - is more expensive and slower.