HalGuard's slick-looking fire extinguishers were originally developed for auto-racing. The "clean", electrically non-conductive cleaning agent they use, called Halotron 1, is perfect for not destroying wiring and electronics. It quickly transforms into a gas, leaving no icky residue after use.
Halotron 1, which is EPA and FAA approved, even stores longer than powder-based extinguishing agents. HalGuard's fire extinguishers are available in two sizes, 1.4 lbs or 2.5 lbs, and pricing ranges from $125 to $170. [AutoSport via Uncrate]