The pager is worth it if you want to be a stress case, worring each time the pager goes off maybe twice a day. Plus you're paying $200-$300 to add that stress to your life.
I purchased my bike alarm off of ebay for all of $40. Laugh if you will but it's a very good alarm. It has never had any momentary failures in the two years i've had it. It is hard wired into the wiring harness of the bike, and hides nicely as the siren and the box are small. The range on the remote is 175 feet and has no problems transmitting from the inside of my home. It has remote start for fuel injected bikes ( ignition key need not be in the switch), will work on a carbed bike if the bike is 100% tuned right. If the bike is tilted off the sidestand the alarm will usually sound. If the bike is "hot wired" it still won't start. It also has a code jumping feature. It comes with two key fobs. If someone tries to slightly move the bike the alarm does it's job. And i don't worry about the bike - like if I had a trasmitter that warns me each time a cat or a strong wind sets the alarm off. As with any alarm, use a good motorcycle cable or chain lock. Check with your insurance company and you may be able to recieve a discount for having anti-theft devices.