Once you ascertain your need for a satellite phone, your first decision will be either to rent or to own. While renting a TV no longer makes much sense, renting a satellite phone may be just the ticket for your needs and budget. Some phones rent for about the cost of a rental car at $20 per day. For a week it is anywhere from $40 to $100 and a month $150 and up. The minutes you are actually on the phone can start as little as $1.00 per minute and range up to $2.00. Make sure you include the little extra for another backup battery. You might find yourself in a place where you need to call but your battery is dead and there is no convenient source of power (or no source at all). For the once in a while user, renting might make the most financial sense.
If you don't have the budget for a state of the art satellite phone and data kit (allowing you to transmit data as well ala the internet) which can run to over $9,000, think about purchasing a used phone. You can find these on the internet with satellite service providers.