It depends
"An "atomic" clock is maybe $2,000. I've not checked lately. Could be less. "
It depends on what you want. A rubidium clock is comparatively cheap, but they aren't quite as precise as caesium clocks. The later still costs 50k new and regularly requires changing the tube inside of it. That's to expensive to put in every cell-tower, but not a problem for a TV station which already pays 100k for a camera and another 100k for the lens.
"One GHz terrestrial system I know has an oven based "clock reference" only in the main mast and then the clients lock to a pilot carrier for stability, to save £100 per unit."
That's also standard for mobile phones, otherwise you couldn't get the carrier precise enough.
Frying all the satellites is unlikely, BTW, as half of them are on the "night" side of earth. The failures I've found so far were only temporary.
Biting the hand that feeds IT
