actually not, because the sale still end up at 13, which is within the range.

Looked into Sale 9, here's what matches:

https://backpack.tf/item/185519148 <-- Procedure Mask(2.28)

https://backpack.tf/item/442042631 <-- Widowmaker(8.05)

https://backpack.tf/item/1271479690 < Genuine Sophisticate(7.61)

https://backpack.tf/item/4237978200 <-- Heat of Winter(7.82)

https://backpack.tf/item/916475667 <-- Escape Plan(12.94)

Total is 38.7 ref, or about 1.09 keys.

Everything ends up in a different bp, or in the case of Clubsy, sold with the ref going to other bp.

In Sale 8:

https://backpack.tf/profiles/76561198277620182#!/compare/1535673600/1535932800

https://backpack.tf/item/112330222 <-- V Gunboats(4.28)

https://backpack.tf/item/203798555 <-- V Hound Dog(22)

https://backpack.tf/item/574625861 <-- G Cold War(7)

https://backpack.tf/item/694399691 <-- G Merc Medal(4.5)

https://backpack.tf/item/1280235293 <-- Festivized KS Tomislav(27.33)

https://backpack.tf/item/1501076223 <--- KS G Freedom Staff(6.88)

https://backpack.tf/item/3338236445 <-- SF Bonesaw(13.11)

https://backpack.tf/item/3480137473 <--- S KS Fists of Steel(3.88)

https://backpack.tf/item/3955397831 <-- Sniper Rifle(18.85)

https://backpack.tf/item/6705233270 <-- S Down Tundra Coat (6.88)

Note im taking buyer price for some of this stuff as Seller sold stuff quickly to bots.

Total is 114.77 ref, or about 3.24 keys.

So that sale should be 14.5, which conicidentally line up with that mystery 15.

On the topic of the 15, It looks like that is a error on my part from the first iteration of this suggestion. If you look at the YWN sale there, I had not finished typing it, and had made the mistake of adding the value instead of subtracting it.

It could also be a mistype from back then, simply because of the amount of open suggestions I have.

Because otherwise I somehow predicted ahead of time that it was supposed to be 15.