..I bought it directly from
http://lockalarm.com/. I think it was around $44. I got the one with the 30' cable in case the satellite antenna had to be a bit away from the trailer.
It would definitely work for your bike (wrap it around the frame), but I don't know where you'd put it on the kayak. I'm very happy with the quality and the very LOUD alarm. The alarm sounds if the cable is cut or if the lock box is tampered with.
You must register your keys with the company in order to ever receive a replacement if the originals (2) are lost.
PS: I just checked my invoice - it was $44.99 plus $9.99 shipping (shipped from an international location).
..