The SPOT looks pretty good and is cheap. I saw it in the USA for $149 plus a $50 mail in rebate. In Europe it is about £150 then €90 / year for the satellite subscription which allows unlimited tracking.
I'm going to get one as although it is not an ELT, it is as good as and more useful in everyday life (i.e. hopefully an ELT will never be used). The 911 option goes to the nearest centre to your location who then inform the emergency services. The tracking allows anyone you choose to allow to be able to track you and the "check in" feature seems like a good option.
I was flying over the desert close to the mexican border a couple of days ago, no flight plan and no flight following. Sand dunes and nothing else there, we (stupidly) had no water on the aeroplane, no survival equipment, and were in shorts. It was 40C, and there was nothing for miles. Had we gone down we'd have been dead, unless picked up very quickly. Built in ELT combined with SPOT seems like a good investment (along with the $150 survival bag from REI
)