Delorme inReach SE. Garmin bought them a few years ago, but it seems they've got a massive stockpile of the old Delorme-branded devices for half what the new Garmin ones go for. $10 cheaper at gpscity than Amazon:
Rated 4.6/5. Low prices, reviews, videos and more for the DeLorme inReach SE, a DeLorme Tracking GPS item.
The inReach gives you two-way messaging, as well as the ability to actually write out messages (as opposed to the Spot, which is just a couple of buttons for preset messages). If you don't need the live tracking and are willing to pay for each message sent (ie. it's mainly for getting rescued in an emergency) then the $12/mo plan ("Safety") is pretty reasonable. This week I committed to the $25/mo plan ("Recreation") with an annual contract which allows for unlimited tracking (viewable online) and sending preset messages. You can also pay more per month and have the ability to suspend the service when you're not using it, but the break-even point is about 8 months.