Warhawk skins are a family of skins in CS:GO currently featuring only one member - Glock-18 | Warhawk. The skin features a custom paint job that was clearly inspired by the airplanes from the war of the previous era, and can be obtained by opening the Horizon Case. It is available in all five exteriors and each of them can have the StatTrak technology attached to it.
When it comes to the price, Warhawk skins can range from a few cents to a few dollars depending on the exterior.
Check out other CS:GO skins families: