I did a
DIY controller, and bought a strap from Scopestuff in the US for $35.00. Total cost around $50 for the lot. Since I made the controller, I haven't had a single night where I've had to use it.
You can also roll your own either with resistors or Nichrome wire.
This site has a circuit diagram and details on how to make a heater with nichrome wire and silicone tubing. Some of the other guys have used an off the shelf kit from DSE or Jaycar, you should be able to get details by doing a search of the forum.
