http://www.scorpioalarms.com
I have one of these alarms. So far it has worked well. That is, the bike is still here and those that know about the alarm dont stand around my bike (because the perimeter sensor tells them to piss off). To that degree I really like it. The pager works very well, a little difficult to learn how to use it (secret button combinations like a PS2 game), but worth the effort for the flexibility in arming. Plus it has an awesome range.
I consider this to be the best sort of alarm (short of a GPS unit). With perimiter, ignition, shock, tilt, battery back-up, pager and so on.
I bought mine when the aussie dollar was about 4-5c stronger. But, its still better value than a locally available alarm (those that I have seen).