On other side

https://backpack.tf/profiles/76561198089631701#!/compare/1609372800/1609632000

400 pure

I don't see where 350 came from. If it was from one of the October sales, neither of those had fully updated hats

https://backpack.tf/profiles/76561198254882979#!/compare/1602720000/1602806400 - G. Fetti Hazmat + 40 Keys

https://backpack.tf/profiles/76561198089631701#!/compare/1602633600/1602806400 - Added 14 Keys for 4 Unusuals

The second sale can't be used because the only Sack and Buddy sales aren't traceable.

The Hazmat's sales were pretty discrepant at the time, so that sale can be excluded as well.

I also can't tell what you sold this for

https://backpack.tf/profiles/76561198257109478#!/compare/1609632000/1609804800

https://backpack.tf/profiles/76561198336460737#!/compare/1609632000/1609804800

If you sold this for a valid amount, your sale can be included. Otherwise, 400 flat will work here.

Either way, this suggestion will need to be closed.

Might be taking into account a previous sale, but would need minis. Sale is outdated but maybe not too far considering rarity of the hat:

https://backpack.tf/profiles/76561198089631701#!/compare/1602633600/1608163200

(Sale for roboactive doctor's sack + chiroptera venenata little buddy + death at dusk pirate bandana + sparkling lights bumble beenie, with seller adding 14 keys on his side.)