ADS-C costs

[Macc21st]

Hi,
Anybody knows the current OPEX, for airlines, of ADS-C?

According to Inmarsat it is USD 1 per flight hour:

Inmarsat - Aviation (http://www.inmarsat.com/inm/nl/aviation/jul/safety-services-and-flight-ops.html)

But I doubt it is so low, otherwise airlines would use it more (specially if they already have FANS 1/A installed).

Thanks in advance,
Macc