The Fastloc GPS gives 3bytes (sat# + RSSI) per satellite, with a maximum of 12 satellites per acquirement. We currently use 8 sats (24bytes) per measurement as we found it enough to give a precise position.
The Fastloc is not used for continuous measurements, it is to be used on a trigger thus consuming very low power. (30ms+12s)
Its only meant for applications where power is the most important variable in the equation not cost nor speed.
The cost is prohibitive for hobby work. We are talking of £1k per unit.