item1:

https://backpack.tf/item/12796211733

sale1:

https://backpack.tf/profiles/76561198850121720#!/compare/1687132800/1687219200

https://backpack.tf/profiles/76561198276793785#!/compare/1686096000/1687392000

12 keys

sale2:

https://backpack.tf/item/12774653894

sale1:

https://backpack.tf/profiles/76561199017719018#!/compare/1686614400/1686960000

https://backpack.tf/profiles/76561198342547469#!/compare/1686614400/1686700800

?

item2:

https://backpack.tf/item/12136814626

sale1:

https://backpack.tf/profiles/76561198314776045#!/compare/1686700800/1686787200

https://backpack.tf/profiles/76561198171698314#!/compare/1686700800/1686873600

?

item3:

https://backpack.tf/item/11984031120

sale1:

https://backpack.tf/profiles/76561198039399614#!/compare/1686268800/1686873600

https://backpack.tf/profiles/76561199029954324#!/compare/1687564800/1688083200

?

item4:

https://backpack.tf/item/11935298333

sale1:

https://backpack.tf/profiles/76561199111073161#!/compare/1689379200/1689724800

?

gamble

https://marketplace.tf/items/tf2/31282;5;u61

sale1:

2023-06-26

29.99/2.002=14.9800

15 keys

sale2:

2023-07-10

34.99/1.96=17.85

18 keys

sale3:

2023-09-01

39.99/2.025=19.74814

20 keys

12, 15, 18, 20

Mindacos:

Sale 2 on Item 1 is more straightforward than you think. It sold for that C.A.P.P.E.R, which seems to have been around 7-9 Keys at the time.

12 already felt low with an active buyer at 12 Keys, but knowing it ended up reselling for less makes it even more of an outlier here. Conversely, these sales happening also make 20 Keys feel high in contrast.

15-18 should be fine here.