The third option is to cancel your text plan, which I have done. If my friends send me a text, it disappears into the ether (no error message). I'm trying to get folks used to contacting me through any other means (email, fb, g+, gchat, call me...maybe?).
A single SMS in the US can cost 40 cents, since both the sender and receiver will pay if they don't have bulk plans. Any message containing more than one SMS worth of information would be cheaper to send by first class mail, although the SMS does win for anything short enough to fit into one message.
Maybe there are costlier satellite data plans. A quick search of Iridium's plans revealed no prices, just resellers and offers of quotes, which indicates it may be really pricey.