Sale 1:

Sold for 25 keys (ID’s match)

Seller: https://backpack.tf/profiles/76561198067397074#!/compare/1511136000/1511222400

Buyer: https://backpack.tf/profiles/76561198077824457#!/compare/1511049600/1511222400

X = 25

Sale 2:

Sold for 24 keys

Seller: https://backpack.tf/profiles/76561198081466207#!/compare/1509580800/1509926400

Buyer: https://backpack.tf/profiles/76561198353800911#!/compare/1509840000/1509926400

X = 24

Sale 3:

Sold for 21 keys in a day

Seller: https://backpack.tf/profiles/76561198337734785#!/compare/1510358400/1510444800

Buyer: https://backpack.tf/profiles/76561198044000011#!/compare/1510272000/1510444800

The item history on the Modest shows that it was owned for quite a while, but that’s only because the previous owner hadn’t had their backpack scanned for a while.

https://backpack.tf/profiles/76561198337734785#!/compare/1510272000/1510358400 - This compare link shows that it was obtained a day before the sale at 21 keys.

X = 21

Sale 4:

Sold with ~3 keys in items for Ancient Eldritch Smokey Sombrero (In-date at 24.5, sellers at 22.5-23, taking 23.5) + cheap items

No outpost

Seller: https://backpack.tf/profiles/76561198170440245#!/compare/1505692800/1505779200

Buyer: https://backpack.tf/profiles/76561198110747621#!/compare/1505692800/1505779200

X = 20

Sale 5:

Bulk for Amaranthine Plug-in prospector

Seller: https://backpack.tf/profiles/76561198110747621#!/compare/1505692800/1505779200

Buyer: https://backpack.tf/profiles/76561198179707937#!/compare/1505692800/1505779200

Sale 6:

Sold with 25 keys for Neutron Star Coldsnap Cap

Seller: https://backpack.tf/profiles/76561198353800911#!/compare/1511568000/1511654400

Buyer: https://backpack.tf/profiles/76561198086948995#!/compare/1511568000/1511654400

Should be used on the Coldsnap.

Sellers:

28 keys

https://i.imgur.com/sJQUnGG.png

30 keys:

https://i.imgur.com/RPgnars.png - 1 month

https://i.imgur.com/EGPJspv.png - 10 months

Sales at:

20

21

24

25

21 quicksold, excluding 20 and 21.

Going with 24-25.