Sale #1:

https://backpack.tf/profiles/76561198429571439#!/compare/1548374400/1548720000

Sold for a Terror-Watt Virtual Reality Headset (21 keys)

21 keys

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Sale #2:

https://backpack.tf/profiles/76561198182213262#!/compare/1547683200/1547769600

Sold for 21 keys.

21 keys

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Sale #3:

https://backpack.tf/profiles/76561198363018510#!/compare/1543190400/1543449600

???

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Minis:

Terror-Watt Virtual Reality Headset:

https://backpack.tf/profiles/76561198334451855#!/compare/1543968000/1544054400

Sold for a Duped Max's Severed Head (21 keys)

21 keys

I am unable to find a mini for the Max's severed head, so I'll say it's ~21 keys.