"You say Bug Out as in disaster, you only have one real choice right now, Iridium. The other similar satphone is Globalstar and I DO NOT recommend them because they have serious problems with their network as in you cant get on the network to make a call."
+1, Sidewinder6. We take them on remote canoe trips, and after using both, I'd never take another Globalstar phone -- not reliable at all.
But, yes, they are fiendishly expensive, not only to buy the units, but for the monthly subscription: $35-40 per month for a basic subscription, and no minutes included with that -- calls are billed at rates starting around $1.30/minute for calls to other iridium phones, going up from there to about $10.00/minute for calls to phones on that other sat network...
You can get prepaid cards, but they're time-limited: e.g., a one-year card with 500 minutes costs $625.
That's a big ongoing investment, for something you hope never to need. I'd go with CB radios, myself.