Np,
I for the life of me cannot find any others bar the Innovative ones. Theres a Supra tuning mob in Colorado Springs, one of Titan Motorsport's competitors, that used to cut their own heatsinks. There was also a Honda place in Canada, Vteck Sports or something, that i swear used to hock them. Commonly available... as in from the US, not cheap from kmart
I cant tell you if a heatsink would dissipate enough heat, as it depends a lot on your driving style and use for the car. Only recently i was reading a story bout a guy who had the sensor in a heatsink just before the CAT, and he was still killing them, so...