Resuggestion

Sale 1

Sold for 80 keys pure of a clean Sunbeams Chieftain's Challenge

https://backpack.tf/profiles/76561198203872345#!/compare/1520380800/1520553600

Sale 2

https://backpack.tf/profiles/76561198043936328#!/compare/1517702400/1517788800

Sold for a Purple Energy Western Wear (40 keys) Sunbeams German Gonzila (46 keys) and 1 pure key = 87 keys B/O

Sale 3

https://backpack.tf/profiles/76561198119149660#!/compare/1518048000/1518134400

Sold for a Terror-Watt Reggaelator (26.5 keys) Haunted Ghosts Football Helmet (19 keys) Circling Peace Sign Safe'n'Sound (18 keys) Blizzardy Storm Human Cannonball (23.5 keys) = 87 keys in total overpay B/O

The B/O for Sale 3: https://backpack.tf/profiles/76561198047941585#!/compare/1518048000/1518134400

Sale 4

https://backpack.tf/profiles/76561198047941585#!/compare/1519776000/1519862400

Sold for a Showstopper Taunt: Square Dance (64 keys) and 34 keys = 94 keys of overpay B/O

The B/O for Sale 4: https://backpack.tf/profiles/76561198203872345#!/compare/1519776000/1519862400

Conclusion

The new price for the Sunbeams Chieftain's Challenge still remains 80 keys because it is due to the unusual being purchased for 80 keys in pure. Also, 25% of this suggestion is purchased in pure while the 75% is purchased as in overpay or mixed offers and will be marked as a B/O.

Side Note: You may add extra evidence to support this suggestion.