I like Polar

Bear me the pun

Sellers: - https://gyazo.com/d7082437da97b77db1d81874ad4c54da

https://backpack.tf/item/6489582813 - Young @ 27 Keys

https://backpack.tf/item/6566366936 - 1 Day @ 27 Keys

Sale 1)

https://marketplace.tf/items/tf2/30958;5;u10 + https://backpack.tf/item/7238541111 - (Quick)Sold for ~(28) Keys ($49.99 / $1.78)

No Buyout

Sale 2)

https://backpack.tf/profiles/76561198072439676#!/compare/1564012800/1564099200 - Untrace

Sale 3)

https://backpack.tf/profiles/76561198280357510#!/compare/1563926400/1564012800

https://backpack.tf/profiles/76561198072439676#!/compare/1563753600/1564012800 - Bulky

Sale 4)

https://backpack.tf/profiles/76561198176352293#!/compare/1563408000/1563840000

https://backpack.tf/profiles/76561198280357510#!/compare/1563321600/1563408000 - Bulky

Sale 5)

https://backpack.tf/item/7198206161 + https://marketplace.tf/items/tf2/30958;5;u10 - (Quick)Sold for ~(25) Keys ($44.99 / $1.83)

Sale 6)

https://backpack.tf/profiles/76561198130185987#!/compare/1562716800/1563408000

https://backpack.tf/profiles/76561198043936328#!/compare/1562630400/1562716800 - Untrace

Sale 7)

https://backpack.tf/profiles/76561198021867575#!/compare/1567814400/1567900800 - Untrace

Sale 8)

https://backpack.tf/profiles/76561198059674778#!/compare/1567900800/1568073600 - Sold for a Green Confetti Modest Metal Pile of Scrap (21.5) = (22) Keys

No Buyout

Sale 9)

https://backpack.tf/profiles/76561198069493147#!/compare/1566604800/1566691200

https://backpack.tf/profiles/76561198059674778#!/compare/1566604800/1566691200 - Sold for a Purple Energy Archer's Sterling (29.5) + ~2.5 Keys in Sweets = 32 Keys, Caps at Buyout

Buyout was (27) Keys - https://bot.tf/stats/listings/MGZPO3D2

Sale 10)

https://backpack.tf/profiles/76561198069493147#!/compare/1566259200/1566345600

https://backpack.tf/profiles/76561198981736558#!/compare/1566259200/1566345600 - Sold for X Keys

Sale 11)

https://backpack.tf/profiles/76561198238814252#!/compare/1566172800/1566259200 - Untrace

Sale 12)

https://backpack.tf/profiles/76561198004952793#!/compare/1566000000/1566086400

https://backpack.tf/profiles/76561198238814252#!/compare/1566000000/1566086400 - Sold for a Sunbeams Doctor's Sack + ~0.5 Keys in Sweets + 2 Keys - Using there

Buyout was 28 Keys - https://bot.tf/stats/listings/Y9G62R7W

Sale 13)

https://backpack.tf/profiles/76561198374540031#!/compare/1564963200/1565136000

https://backpack.tf/profiles/76561198004952793#!/compare/1564963200/1565136000 - Sold with ~0.7 Keys in Sweets for a Disco Beat Down Backbiter's Billycock - Lower than buyers with billycock seller at 18.5 - https://gyazo.com/323e07b90eb50ab36fa9505d29cde895

Sale 14)

https://backpack.tf/profiles/76561198267189538#!/compare/1563062400/1563148800

https://backpack.tf/profiles/76561198374540031#!/compare/1563148800/1563235200 - Untrace

Sale 15)

https://backpack.tf/profiles/76561198267189538#!/compare/1562630400/1562716800 - Sold to a Quickbuyer for X Keys

Sale 16)

https://backpack.tf/profiles/76561198114924746#!/compare/1562544000/1562630400 - Low with seller at 17 Keys - https://gyazo.com/1fb2ddc4d4ebe89c06858df822f5efdd

Sale 17)

https://backpack.tf/profiles/76561198314349856#!/compare/1567987200/1568246400 - Bulky

Sale 18)

https://backpack.tf/profiles/76561198861630295#!/compare/1567900800/1567987200

https://backpack.tf/profiles/76561198314349856#!/compare/1567900800/1567987200 - Sold with 10 Keys for a The Dark Doorway Highway Star (36) = (26) Keys

No Buyout

Sale 19)

https://backpack.tf/profiles/76561198156255538#!/compare/1567296000/1567382400

https://backpack.tf/profiles/76561198861630295#!/compare/1567382400/1567468800 - Sold for a Vicious Circle Highway Star (16.5) + An Electric Hat Protector Phononaut - Caps easily

Buyout was (22) Keys - https://bot.tf/stats/listings/4OVQGRPG

Sale 20)

https://backpack.tf/profiles/76561198156255538#!/compare/1566691200/1566777600 - Quicksold for X Keys

Sale 21)

https://backpack.tf/profiles/76561198090750997#!/compare/1566604800/1566691200 - Sold for X Keys

Sale 22)

https://backpack.tf/profiles/76561198030019084#!/compare/1566086400/1566172800

https://backpack.tf/profiles/76561198090750997#!/compare/1566086400/1566172800 - Sold for (23) Keys

Sale 23)

https://marketplace.tf/items/tf2/30958;5;u10 - Sold for ~(30) Keys ($55.64 / $1.84)

Sales we have are:

22, 22, 23, 25, 26, 27, 28 and 30

Nothing seems an obvious outlier here

Thanks =)