4 years

Sale #1:

https://backpack.tf/profiles/76561198085861958#!/compare/1763164800/1763251200

https://backpack.tf/profiles/76561198344640234#!/compare/1762905600/1763251200 ~ bulk for a burning croens

Sale #2:

https://backpack.tf/item/1212009069

https://backpack.tf/profiles/76561198199284954#!/compare/1760054400/1760227200

https://backpack.tf/profiles/76561198344640234#!/compare/1756512000/1760140800

Only 7 days outdated, on a high tier hat like this thats outdated by 4 years, seems fine to be used.

https://imgur.com/a/s2ri9ss

Sulphurous Conjurer's Cowl (370) + Nether Trail Hellmet ( https://backpack.tf/suggestion/696af4fd73231e890103d756 ~ 88.5) + Anti-Freeze Napper's Respite (no usable sales, taking buyers at 167 https://i.imgur.com/RxivzdI.png) + 5 keys + max head (26)

= 656.5 keys

Guideline - for hats 200-1000 keys, please round to the nearest 10 keys