Resuggestion, thanks to Mindacos for the info!

Sale 1:

https://backpack.tf/profiles/76561198262993846#!/compare/1534464000/1534636800

SCM

Sale 2:

https://backpack.tf/profiles/76561198262993846#!/compare/1535155200/1535241600

QS

Sale 3:

https://backpack.tf/profiles/76561198187728290#!/compare/1534636800/1534723200

https://backpack.tf/profiles/76561198006544512#!/compare/1534636800/1534723200

Sold for 7 keys + 9 ref

Sale 4:

https://backpack.tf/profiles/76561198306724981#!/compare/1534982400/1535068800

https://backpack.tf/profiles/76561198015384426#!/compare/1534636800/1534982400

Bulky?

Sale 5:

https://backpack.tf/profiles/76561198291006080#!/compare/1533772800/1534032000

https://backpack.tf/profiles/76561198006544512#!/compare/1533686400/1533772800

Untrace.

Sale 9:

https://backpack.tf/profiles/76561198121830870#!/compare/1532736000/1532822400

https://backpack.tf/profiles/76561198291006080#!/compare/1533081600/1533168000

Untrace.

Sale 10:

https://backpack.tf/profiles/76561198190685530#!/compare/1530057600/1530316800

https://backpack.tf/profiles/76561198093230303#!/compare/1530230400/1530316800

Untrace.

Sale 11:

https://backpack.tf/profiles/76561198093230303#!/compare/1530230400/1530316800

https://backpack.tf/profiles/76561198025486280#!/compare/1530230400/1530316800

Sold for 11 keys

Sale 12:

https://backpack.tf/profiles/76561198006544512#!/compare/1535414400/1535500800

https://backpack.tf/profiles/76561198041006430#!/compare/1535414400/1535500800

Sold for 10 keys.

Sale 13:

https://backpack.tf/profiles/76561198041006430#!/compare/1536192000/1536278400

https://backpack.tf/profiles/76561198370447374#!/compare/1536192000/1536278400

Bulk.

Sale 14:

https://backpack.tf/profiles/76561198370447374#!/compare/1536624000/1536710400

https://backpack.tf/profiles/76561198315588518#!/compare/1536624000/1536710400

Sold for 7 keys(QS to bot)

Total sales @:

~7, 11

https://i.imgur.com/pBgxvwW.jpg

Seller at 10, young.

https://backpack.tf/item/6956266159

Buyers up to ~7 keys

Mindacos' Part:

it looks like 7-11 should be fine here. Wide range that covers the market shifts that this hat has gone through, conveniently enough.