The beacon we used belonged to my friend, and I didn’t ask how much it cost, but I understand that you have to buy the unit and then pay a subscription to use the service. The cost of that subscription depends on the level of support you want. The automatic OK messages come as part of the package, and there is a manual OK button you can press which will send the usual message and location, with a tag that it was generated manually. If you injure yourself and the unit is not damaged, it will continue to generate OK messages, but the location won’t change. The manual message confirms you are still conscious, and this service is also included in the subscription. It is possible to send SMS using the unit, but this is very expensive. When summoning help, you may get charged by the rescue team, and the subscription includes insurance against these costs, and a guaranteed level of SAR should it become necessary. I don’t know how much these subscriptions cost either, but I can’t imagine they’re cheap!