Bubbly Brainiac

Sale 1: 69 pure

https://backpack.tf/profiles/76561198115721685#!/compare/1645228800/1645315200

https://backpack.tf/profiles/76561198048792033#!/compare/1645315200/1645401600

Sale 2: 80 pure

https://backpack.tf/profiles/76561198158206236#!/compare/1646524800/1646784000

https://backpack.tf/profiles/76561198828548568#!/compare/1646611200/1647043200

Sale 3: 66 pure

https://backpack.tf/profiles/76561198133606132#!/compare/1645488000/1645660800

https://backpack.tf/profiles/76561198376885782#!/compare/1645574400/1645660800

Sales 4/5: untrace

https://backpack.tf/profiles/76561198115721685#!/compare/1645401600/1645488000

https://backpack.tf/profiles/76561198453530349#!/compare/1645401600/1645488000

https://backpack.tf/profiles/76561198337734785#!/compare/1645401600/1645488000

Sale 6: bulk w/ skinport bot

https://backpack.tf/profiles/76561198376885782#!/compare/1646697600/1646784000

Sale 7: marketplace

https://marketplace.tf/items/tf2/590;5;u34

https://manic.tf/keyprice/?at=2022-02-28&site=marketplace.tf

$150 / $1.75 = 85.71 keys

Sale 8: steaming brainiac 1 for 1

https://backpack.tf/profiles/76561198301049636#!/compare/1646524800/1646611200

https://backpack.tf/profiles/76561198281630040#!/compare/1646524800/1646611200

Sale 9: bubbling brainiac + pmoon handy thing = ethereal essence mr. bones

https://backpack.tf/profiles/76561198331167728#!/compare/1644537600/1644624000

https://backpack.tf/profiles/76561198140316312#!/compare/1644537600/1644624000

There is a sell order at 79 keys listed since 3/8/22 and one at 80 keys listed since 2/12/22

https://backpack.tf/classifieds?item=Brainiac%20Hairpiece&quality=5&tradable=1&craftable=1&australium=-1&particle=34&killstreak_tier=0

going with 66-79

closing this, as the buyer from the 2nd sale has listed theirs at 75