Several histories with in-date sales, also you should if possible screenshots of trades with this hat or comparison links etc. Furthermore, not sure where u got the 12-13 range from, if its a SCM sale just find price of key then do 26 / (price of key).

https://backpack.tf/item/9097750201

https://backpack.tf/item/8944133265

https://backpack.tf/item/8278013885

You'll also need to check the compares for those item histories too. In an unusual suggestion you need to include every sale in the past 90 days (3 months)