One of the most expensive mosquito repellents currently on the market is the mosquito magnet. Mosquito magnets operate by emitting a stream of carbon dioxide, heat, moisture and octenol which is generated through a propane tank. Once a mosquito flies within range of the mosquito magnet, it sucks them into its net where it traps, dehydrates and kills them. Mosquito magnets are powered by propane and therefore do not require any electricity, electrical outlet or extension cords. This form of mosquito repellent is mobile and can be taken on camping trips or placed anywhere throughout your yard. American biophysics claims there mosquito magnets, the Mosquito Magnet Liberty and the Lentek Mosquito Trap are extremely effective in eliminating mosquitoes. Mosquito magnets can cost anywhere from $250 to $700 online.