Resubmission of my previous suggestion, as I've only just noticed I got my wires crossed and noted down the sweets in Sale 1 as being traded for this hat, when they were actually on the seller side.

Item History - https://backpack.tf/item/7295773278

Sale 1 - Sold with a few keys in sweets for a Phosphorous Cotton Head.

https://backpack.tf/profiles/76561198114151975#!/compare/1715385600/1715472000

https://backpack.tf/profiles/76561198035464165#!/compare/1715385600/1715472000

Cotton Head is still in-date at 250 keys. Just gonna take the monthly SCM average on the Unusualifiers, which is £1.71 for the Burstchester and £2.98 for the Russian Arms Race (x2). £7.69 total, current key price is £1.68. Comes to 4.577 keys, rounding up to five. 250 - 5 takes this sale to 245 keys.

Sale 2 -

Sold for a Purple Energy Brothers in Blues, a Bubbling Large Luchadore, and a Pastel Trance Conga.

https://backpack.tf/profiles/76561198108020471#!/compare/1715904000/1715990400

https://backpack.tf/profiles/76561198035464165#!/compare/1715904000/1715990400

Conga has a solid in-date suggestion at 59, using that. - https://backpack.tf/suggestion/6630ef8e72c7657c100b3e6a

Mini for the Brothers in Blues @ 92.5 - https://backpack.tf/suggestion/6648dd43ce355784ce031396

Only traceable in-date I can find on the Luchadore was my own purchase of it for 107 keys pure.

https://backpack.tf/profiles/76561199581722058#!/compare/1710028800/1710201600

https://backpack.tf/profiles/76561198108020471#!/compare/1710028800/1710201600

107 + 92.5 + 59 = 258.5, rounding up to 260.

Sale 3 - 102 pure keys. Calling a quicksell as it went the same day it was listed by the bot, hours after being sold to the buy order.

https://backpack.tf/profiles/76561198378207723#!/compare/1714953600/1715040000

https://backpack.tf/profiles/76561198114151975#!/compare/1714953600/1715040000

Sale 4 - 93 keys pure and 43 refined. Buy orders counter. Rounds up to 94.

https://backpack.tf/profiles/76561198390036943#!/compare/1709942400/1715040000

https://backpack.tf/profiles/76561198378207723#!/compare/1714953600/1715040000

So we've got 245, 260, 102 and 94. 102 is justified marking as a quicksell, and 94 was a dump to a buy order bot. Taking 245-260 as the final range.