You might also look at the geocaching community. They might make for some great partners to get the word out about your startup's use & potential to a slice of your target market. Probably just need to coordinate some event(s) and donate/lend some of your hardware and you could find some loyal fans.
Not sure if it'd work out or be worth it, of course, but an idea.
Not sure if it'd work out or be worth it, of course, but an idea.