Judging from what I read on their website and my experience with ELT's, DFing one of these on the ground with the equipment they describe would be a very slow process. And if you're close enough to be in range, you're probably standing on the person you're looking for.

Perhaps they should call it a BLB - "Body Locator Beacon"

Donate the $150 to your local SAR team to help support their air-scent search dogs. Its a much better investment. Both methods require someone to know you're missing and both need to get pretty close to you before they start working. But the dog will find you faster and you don't have to carry or activate a beacon.