Re-suggesting due to foamy's info here:

https://backpack.tf/suggestion/5cd11f2e6780721d8e71a374#comment-5cfd68d2d381721a993e5b4e

Sale 1: Bulk.

https://backpack.tf/profiles/76561198108181159#!/compare/1549584000/1550275200

https://backpack.tf/profiles/76561198080714795#!/compare/1549497600/1549584000

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Sale 2: ~18 Keys.

Sold For 17 Keys Pure And 1 Key In Sweets.

https://backpack.tf/profiles/76561198080714795#!/compare/1550620800/1550707200

https://backpack.tf/profiles/76561198294426922#!/compare/1550620800/1550707200

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Sale 3: ~23 Keys.

Sold For Isotope Professional Killstreak Blue Mew SMG (Field-Tested) (13) + Strange Professional Killstreak Wrench. (Lowest Seller 12,

Highest Buy Order 7 [12+7/2=9.5] Rounding to 10)

13+10=23

https://backpack.tf/profiles/76561198294426922#!/compare/1550707200/1550793600

https://backpack.tf/profiles/76561198280357510#!/compare/1550707200/1550793600

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Sale 4: ~24 Keys.

Sold For Circling Peace Sign Noble Amassment of Hats (19) + Mega Strike Taunt: Deep Fried Desire (4) + 1 Key.

19+4+1=24

https://backpack.tf/profiles/76561198280357510#!/compare/1550793600/1550880000

https://backpack.tf/profiles/76561198208761289#!/compare/1550880000/1556928000

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Sale 5: Untrace.

https://backpack.tf/profiles/76561198208761289#!/compare/1550880000/1550966400

https://backpack.tf/profiles/76561198053717045#!/compare/1550793600/1550880000

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Sales: 18/23/24

Going with 23-24 keys.

Thanks to scourge for the premium!