Exo skins feature a number of metal parts, of varying shapes and sizes, over a purple pattern that is covered with geometrical shapes. There is currently only one skin in this family, and it is Nova | Exo. The skin was added to the game on June 15, 2016, it belongs to The Gamma Collection and was released as part of the Gamma Exposure update. It can be obtained from the Gamma Case. The skin comes in all five exteriors and has the option of adding StatTrak to it.
The price of Exo skins won't exceed $1, even with StatTrak added to it.
Check out other CS:GO skins families: