Thermal Vision

https://backpack.tf/item/319613868

Sale 1) Sold for 48 Keys

https://backpack.tf/profiles/76561198128550841#!/compare/1556496000/1556582400

Sale 2) Sold + Duped Cloud 9 A Rather Festive Tree + 2 Keys for an Eldritch Opening Puffy Polar Cap

https://backpack.tf/profiles/76561198000102611#!/compare/1558656000/1558742400

Using this for the Puffy.

Sale 3) Sold for $82.99 when Keys were ~$1.80 each

https://marketplace.tf/items/tf2/177;5;u13

https://marketplace.tf/items/tf2/5021;6

82.99 / 1.80 = 46.1, which rounds to 46 Keys

https://backpack.tf/item/1951280602

Sale 4) Sold for $115 when Keys were ~$2.38 each

https://backpack.tf/profiles/76561198074149928#!/compare/1559779200/1559865600

https://backpack.tf/profiles/76561198025010978#!/compare/1559779200/1559865600

https://steamcommunity.com/market/listings/440/Unusual%20Ze%20Goggles

https://steamcommunity.com/market/listings/440/Mann%20Co.%20Supply%20Crate%20Key

115 / 2.38 = 48.31, which rounds to 48 Keys

https://backpack.tf/item/392158078

Sale 5) Sold for $77 when Keys were ~$1.83 each

https://backpack.tf/profiles/76561198046985101#!/compare/1557532800/1558396800

https://marketplace.tf/items/tf2/177;5;u13

https://marketplace.tf/items/tf2/5021;6

77 / 1.83 = 42.07, which rounds to 42 Keys

Sale 6) ?

https://backpack.tf/profiles/76561198046985101#!/compare/1559520000/1559606400

https://backpack.tf/profiles/76561198215053099#!/compare/1559606400/1560038400

Sale 7) ?

https://backpack.tf/profiles/76561198215053099#!/compare/1559606400/1560038400

https://backpack.tf/profiles/76561198020382415#!/compare/1559433600/1559606400

Looks like 40 Keys.

Sale 8) Bulk sale

https://backpack.tf/profiles/76561198020382415#!/compare/1560384000/1560470400

https://backpack.tf/item/418759719

Sale 9) Sold for 47 Keys

https://backpack.tf/profiles/76561198067211253#!/compare/1554163200/1554595200

Sale 10) Gambled

https://backpack.tf/profiles/76561198175019602#!/compare/1554595200/1554681600

https://backpack.tf/profiles/76561198027152204#!/compare/1554595200/1554681600

Sale 11) Gambled

https://backpack.tf/profiles/76561198027152204#!/compare/1554681600/1554768000

Sale 12) Gambled

https://backpack.tf/profiles/76561198016663834#!/compare/1554681600/1554768000

Sale 13) Sold + Duped Circling Heart Rimmed Raincatcher + '72 Schadenfreude + 2 Keys for a Purple Energy Tundra Top

https://backpack.tf/profiles/76561198043662502#!/compare/1554768000/1554854400

https://backpack.tf/profiles/76561198269636307#!/compare/1554768000/1554854400

This sale would be better used for the Top.

Sale 14) Bulk sale for a Burning Flames Trophy Belt

https://backpack.tf/profiles/76561198269636307#!/compare/1554768000/1554854400

Sale 15) Bulk sale for a Spellbound L'homme Burglerre + 13 Keys

https://backpack.tf/profiles/76561198838788284#!/compare/1554940800/1555027200

Sale 16) Sold for a Purple Confetti Master's Yellow Belt (24.5 Keys) + Green Confetti Desert Marauder (13 Keys) + 5 Keys

https://backpack.tf/profiles/76561198055622215#!/compare/1555200000/1555286400

24.5 + 13 + 5 = 42.5, which rounds to 43 Keys

Desert Mini

https://backpack.tf/profiles/76561198196410274#!/compare/1554249600/1554422400 - Sold for 13 Keys

Sale 17) Bulk sale

https://backpack.tf/profiles/76561198056180801#!/compare/1555545600/1555632000

Sale 18) Sold for 45 Keys

https://backpack.tf/profiles/76561198264117106#!/compare/1557014400/1557100800

https://marketplace.tf/items/tf2/177;5;u13 - Sold for $88 when Keys were ~$1.79, $82.46 when Keys were ~$1.81, and $53 (low outlier)

https://marketplace.tf/items/tf2/5021;6

88 / 1.79 = 49.16, which rounds to 49 Keys

82.46 / 1.81 = 45.6, which rounds to 46 Keys

Calling 49 high because of how old the sale was and because of this 23 day seller at 49 Keys -> https://imgur.com/a/7LWaZpH

https://backpack.tf/item/1645415421