Sale 1: Bulk.

https://backpack.tf/profiles/76561198027989151#!/compare/1554595200/1554854400

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sale 2: Bulk.

https://backpack.tf/profiles/76561198067211253#!/compare/1555891200/1555977600

https://backpack.tf/profiles/76561198346664888#!/compare/1555718400/1555891200

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sale 3: QS.

https://backpack.tf/profiles/76561198346664888#!/compare/1555891200/1555977600

https://backpack.tf/profiles/76561198066566813#!/compare/1555804800/1555891200

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sale 4: Bulk.

https://backpack.tf/profiles/76561198001256381#!/compare/1558137600/1558224000

https://backpack.tf/profiles/76561198146579306#!/compare/1558051200/1558137600

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Sale 5: ~9 Keys Pure.

https://backpack.tf/profiles/76561198080179568#!/compare/1554076800/1554163200

https://backpack.tf/profiles/76561198069448527#!/compare/1552953600/1555113600

https://gist.github.com/juliarose/7f45a54264f8961b91cb98605afeae60

https://imgur.com/AaAvQkN

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Marketplace.tf Sales:

https://marketplace.tf/items/30978;5;u35

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Sale 6: ~12 Keys.

May 5

$20.79 / $1.8 = 11.55 keys

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sale 7: 10 Keys.

May 17

$21.00 / $1.83 = 11.48 keys - B/O Cap 10, https://bot.tf/stats/listings/4K762OEY

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Including Sales: 9/10

Going with 9-10 keys.

Thanks to scourge for the premium!