Marketplace Sales:

https://marketplace.tf/items/339;5;u7

https://manic.tf/keyprice/?at=2018-12-15 - $80.08 / $1.64 = 48.83 keys

https://manic.tf/keyprice/?at=2018-12-22 - $119.99 / $1.74 = 68.96 keys

https://manic.tf/keyprice/?at=2019-02-07 - $141 / $1.81 = 77.90 keys

https://manic.tf/keyprice/?at=2019-02-18 - $92.14 / $1.79 = 51.47 keys

https://i.imgur.com/W1avbfC.png - B/O of 80 on the ~78 key sale

X = 78

X = 69

X = 51

X = 49

Other Sales:

https://backpack.tf/item/471898477 (#1)

https://backpack.tf/item/279619682 (#2)

https://backpack.tf/item/209021615 (#3)

https://backpack.tf/item/245762378 - marketplace

#1

Bulk for Cloud 9 Polar Pullover

https://backpack.tf/profiles/76561198084113284#!/compare/1550448000/1550534400

https://backpack.tf/profiles/76561198096856475#!/compare/1550361600/1550534400

#2

Marketplace sale

https://backpack.tf/profiles/76561198043936328#!/compare/1544832000/1544918400

https://backpack.tf/profiles/76561198279244360#!/compare/1545436800/1546560000

#3

Bulk for Green Energy Salty Dog

https://backpack.tf/profiles/76561198084758995#!/compare/1549843200/1550966400

https://backpack.tf/profiles/76561197994697258#!/compare/1550880000/1550966400

Sellers:

https://i.imgur.com/nluqgjL.png (80 key seller already sold)

https://backpack.tf/item/209021615 - 70 keys

https://backpack.tf/item/471898477 - 71 keys

https://backpack.tf/item/245762378 - 74 keys

Sales at:

49

51

69

78

Buyers at 54+, excluding 49 and 51.

Several sellers significantly cheaper than 78, excluding 78.

Going with 69 flat.