Item 1

https://backpack.tf/item/12232901115

Sale 1

https://backpack.tf/profiles/76561198010250846#!/compare/1726704000/1726790400

https://backpack.tf/profiles/76561198057452720#!/compare/1726617600/1726790400

Bulk for a Frostbite Tyrant's Helm

Sale 2

https://backpack.tf/profiles/76561198057452720#!/compare/1729641600/1729814400

https://backpack.tf/profiles/76561198150101707#!/compare/1729728000/1729814400

275 keys

Sale 3

https://backpack.tf/profiles/76561198150101707#!/compare/1731110400/1731542400

https://backpack.tf/profiles/76561199084784906#!/compare/1731369600/1731456000

Dumped for an unknown amount

Sale 4

https://backpack.tf/profiles/76561199084784906#!/compare/1731715200/1731801600

https://backpack.tf/profiles/76561198094238199#!/compare/1731024000/1731801600

No clue

Sale 5

https://backpack.tf/profiles/76561198094238199#!/compare/1731974400/1732060800

https://backpack.tf/profiles/76561197964181994#!/compare/1731542400/1732060800

No clue

Sale 6

https://backpack.tf/profiles/76561197964181994#!/compare/1732060800/1732233600

https://backpack.tf/profiles/76561199020563419#!/compare/1732060800/1732233600

270 keys (15160439658)

Item 2

https://backpack.tf/item/2761853858

Sale 7

https://backpack.tf/profiles/76561198259242019#!/compare/1726272000/1726358400

https://backpack.tf/profiles/76561198094238199#!/compare/1726358400/1726531200

300 keys? (14905947168)

Sale 8

https://backpack.tf/profiles/76561198094238199#!/compare/1728777600/1728950400

https://backpack.tf/profiles/76561198011863913#!/compare/1729209600/1729296000

Buyer inv doesn't go far back enough

Sale 9

https://backpack.tf/profiles/76561198011863913#!/compare/1729555200/1731024000

https://backpack.tf/profiles/76561198220098345#!/compare/1730073600/1730160000

No clue

Sale 10

https://backpack.tf/profiles/76561198220098345#!/compare/1730246400/1730332800

https://backpack.tf/profiles/76561198258001464#!/compare/1730246400/1730332800

Haunted Ghosts Whirly Warrior (272.5) + Max's Severed Head

272.5 + ~36.5 = ~309 keys

Sale 11

https://backpack.tf/profiles/76561198258001464#!/compare/1730592000/1730678400

https://backpack.tf/profiles/76561198252999692#!/compare/1730678400/1730764800

Restless Wraiths Thousand-Yard Stare (120) + 145 keys

120 + 145 = 265 keys

Sale 12

https://backpack.tf/profiles/76561198252999692#!/compare/1730937600/1731283200

https://backpack.tf/profiles/76561198047441117#!/compare/1731196800/1731283200

270 keys

Item 3

https://backpack.tf/item/261953322

Spelled, best not to use

Item 4

https://backpack.tf/item/220611389

Duped, nothing here

Item 5

https://backpack.tf/item/291900272

Sale 13

https://marketplace.tf/items/tf2/98;5;u13

$549.99 / $1.79 = ~307 keys (Nov 30)

Total Sales

265, 270, 270, 275, 300, 307, 309

https://imgur.com/a/nCcypxG

309 - > 265

275 re-dumped for less

Should be fine to round and go with 270 - 310 keys c: