I'd referenced the price list for the Canopy product by Motorola, and the per-component cost of the user-side wireless receiver (not a wireless card, but something like a satellite widget you mount on your roof or windowsill) is $500 -- according to this pricelist.

The extra $30 or so is per-year, per-user software licensing to pay for Motorola's server-side authorization software.

I'm sure you could cobble together something cheaper with enough legwork.