Re-Resuggesting! Thanks to Icycrevasse for the assistance, to PhsaeShifter for providing me with a sale, and to Erik for letting me know what range would be best to take!

Item 1

https://backpack.tf/item/7956467976

Sale #1

Seems to have sold for some keys but only 7 keys + a Pyro Shark, untraceable-

Seller: https://backpack.tf/profiles/76561198993488036#!/compare/1686873600/1686960000

Buyer: https://backpack.tf/profiles/76561198252081876#!/compare/1686873600/1686960000

Sale #2

Sold for a Frozen Icefall Yule Hog (26 keys)-

Seller: https://backpack.tf/profiles/76561198252081876#!/compare/1686960000/1687046400

Buyer: https://backpack.tf/profiles/76561198412907835#!/compare/1686873600/1686960000

Sale #3

Sold for a Strange Kill-a-Watt Shellmet (using this sale to price the shellmet)-

Seller: https://backpack.tf/profiles/76561198412907835#!/compare/1687046400/1687132800

Buyer: https://backpack.tf/profiles/76561198894100456#!/compare/1687046400/1687132800

Sale #4

Seems to have sold for some refined but nothing major shows up, untraceable-

Seller: https://backpack.tf/profiles/76561198894100456#!/compare/1687132800/1688947200

Buyer: https://backpack.tf/profiles/76561198057412106#!/compare/1687046400/1687132800

Sale #5

Sold for an Orbiting Fire Professional's Panama (11 keys) + 12 keys = 23 keys-

Seller: https://backpack.tf/profiles/76561198057412106#!/compare/1687132800/1687219200

Buyer: https://backpack.tf/profiles/76561198847681350#!/compare/1687046400/1687219200

Sale #6

Seems to have sold with some keys but don't know what for, untraceable-

Seller: https://backpack.tf/profiles/76561198847681350#!/compare/1687478400/1687651200

Buyer: https://backpack.tf/profiles/76561199244599385#!/compare/1687564800/1687651200

Sale #7

Sold for 19 keys but probably shouldn't be taken into account given it was a trade back?-

Seller: https://backpack.tf/profiles/76561199244599385#!/compare/1687737600/1687910400

Buyer: https://backpack.tf/profiles/76561198847681350#!/compare/1687651200/1687737600

Sale #8

Untraceable?-

Seller: https://backpack.tf/profiles/76561198847681350#!/compare/1687737600/1687824000

Buyer: https://backpack.tf/profiles/76561198139444147#!/compare/1687737600/1687824000

Sale #9

Sold for 18 keys + 15 refined-

Seller: https://backpack.tf/profiles/76561198139444147#!/compare/1687824000/1687996800

Buyer: https://backpack.tf/profiles/76561199499085206#!/compare/1687564800/1688083200

Sale #10

Sold for 20 keys + a Purple Confetti Missing Piece (8 keys) = 20+8 = 28 keys-

Proof of sale

MP.TF Sale #1

Sold for $89.99 on July 14, 2023

Keys @ $1.95

89.99/1.95 = 46.15ish keys

https://marketplace.tf/items/tf2/600;5;u61

Sales @ 18, 19, 23, 26, 28, 46

Taking 23-26 here