Had to check if my Deep Cover Operator Mini would hold up.

https://backpack.tf/item/5804951467

Brim Sale 1) Sold for a Duped Cloudy Moon Doctor's Sack (40 Keys) + ~1 Key of Mixed

https://backpack.tf/profiles/76561198126979379#!/compare/1510531200/1510617600

40 + 1 = 41 Keys

Sack Mini

https://backpack.tf/profiles/76561198126979379#!/compare/1511654400/1512000000 - Sold for 39 Keys + ~1 Key of Items

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Brim Sale 2) Sold for a Stormy Storm Frickin' Sweet Ninja Hood (40.625 Keys) + ~3 Keys of Items + 1 Key

https://backpack.tf/profiles/76561198031041488#!/compare/1513036800/1513123200 - Buyer's Backpack

40.625 + 3 + 1 = 44.625, which rounds to 45 Keys

Ninja Mini

Ninja Sale 1) Sold for a Terror-Watt Deep Cover Operator (~43 Keys)

https://backpack.tf/profiles/76561198136017741#!/compare/1511568000/1511654400

Deep Cover Operator Macro

https://backpack.tf/item/3540447056

Deep Sale 1) Sold for a Mega Strike Fresh Brewed Victory

https://backpack.tf/profiles/76561198079170528#!/compare/1508371200/1508457600

Ignoring as this is a taunt.

Deep Sale 2) Sold + Mega Strike Deep Fried Desire + 1 Key for a Holy Grail Yeti Punch

https://backpack.tf/profiles/76561198107789076#!/compare/1510012800/1510099200

Ignoring because this sale has 2 taunts.

Deep Sale 3) Sold for a Blizzardy Storm Bonk Boy (41 Keys)

https://backpack.tf/profiles/76561198057330477#!/compare/1510963200/1511049600

https://backpack.tf/item/4866997854

Deep Sale 4) Sold for a Bubbling Gauzed Gaze + Smoking Ol' Guadalajara + Miami Nights Counterfeit Billycock

https://backpack.tf/profiles/76561198255903931#!/compare/1510704000/1510790400

http://www.tf2outpost.com/trade/29442527 - Had a Buyout of 46.5 Keys? Either this sale caps at that or is above 40 Keys and less than 48.25 Keys.

Deep Sale 5) Sold for a Searing Plasma Warhood (29 Keys)

https://backpack.tf/profiles/76561198165742995#!/compare/1511308800/1511395200

Low Outlier.

Warhood Micro

https://imgur.com/a/DEbtD - 1 Day Seller at 29 Keys, 18 Day Seller at 30 Keys, 15 Day Seller at 35 Keys, 7 Day Seller at 40 Keys

https://imgur.com/a/vMd7X - 21 Day Deep Seller at 40 Keys, 6 Day Deep Seller at 40 Keys, 15 Day Deep Seller at 46 Keys, 1 Month Deep Seller at 47 Keys

Ninja Sale 2) Sold for a Power Surge Front Runner + 7 Keys

https://backpack.tf/profiles/76561198031041488#!/compare/1512777600/1512950400 - Buyer's Backpack

This would better be used to price the Front Runner.

Ninja Sale 3) Sold for a Death at Dusk Liquidator's Lid (45.25 Keys) + 3 Keys

https://backpack.tf/profiles/76561198151835897#!/compare/1513036800/1513123200 - Seller's Backpack

https://backpack.tf/profiles/76561198347700081#!/compare/1512950400/1513123200 - Buyer's Backpack

45.25 + 3 = 48.25 Keys

Lid Macro

https://backpack.tf/item/3550080889

Lid Sale 1) Sold + ~2 Keys in Items for a Sunbeams Backbiter's Billycock (39 Keys)

https://backpack.tf/profiles/76561198097135729#!/compare/1512518400/1512604800

39 - 2 = 37 Keys

Billycock Micro

https://imgur.com/a/YwnvK - 5 Day Seller at 39 Keys

Lid Sale 2) Sold for a Power Surge Front Runner + 2 Keys

https://backpack.tf/profiles/76561198066711282#!/compare/1512864000/1512950400

This would better be used for the Front Runner.

Lid Sale 3) Sold + Steaming Master's Yellow Belt (15 Keys) for a Green Black Hole Ye Olde Baker Boy (53.5 Keys) + ~15 Keys of Items

https://backpack.tf/profiles/76561198151835897#!/compare/1513555200/1513641600

53.5 + 15 - 15 = 53.5 Keys

Belt Micro

https://imgur.com/a/eGjhb - 4 Day Seller at 15 Keys

https://backpack.tf/item/3354373181

Lid Sale 4) Sold for a Burning Flames Gentleman's Gatsby (~50 Keys)

https://backpack.tf/profiles/76561198125791160#!/compare/1507680000/1507766400

https://backpack.tf/item/5587278517

Ninja Sale 4) Quicksold for 31 Keys

https://backpack.tf/profiles/76561198318847306#!/compare/1509667200/1509926400

Ninja Sale 5) Sold + 3 Keys for a Burning Flames Buckaroos Hat (40.5 Keys)

https://backpack.tf/profiles/76561198250030346#!/compare/1509753600/1509926400

40.5 - 3 = 37.5 Keys

https://backpack.tf/item/2943955660

Ninja Sale 6) Sold for 33 Keys

https://backpack.tf/profiles/76561198021221797#!/compare/1507420800/1507507200 - Seller's Backpack

https://backpack.tf/profiles/76561198069046514#!/compare/1507420800/1507507200 - Buyer's Backpack

27 of the Keys from the Buyer's Backpack bought the Sulphurous Big Country as seen in the Seller's Backpack:

https://backpack.tf/profiles/76561198116536922#!/compare/1506988800/1507507200

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Brim Sale 3) Sold for a Frostbite Toy Tailor + 2 Keys

https://backpack.tf/profiles/76561198031041488#!/compare/1513123200/1513296000

This would be better used for the Tailor.

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Brim Sale 4) Bulk Sale for a HOUWAR + Keys?

https://backpack.tf/profiles/76561198090602679#!/compare/1513468800/1513555200 - Seller's Backpack

https://backpack.tf/profiles/76561198030413036#!/compare/1513468800/1513555200 - Buyer's Backpack

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Brim Sale 5) Bulk Sale for a Sunbeams Gentleman's Ushanka

https://backpack.tf/profiles/76561198030413036#!/compare/1513555200/1513641600

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https://backpack.tf/item/6224292219

Brim Sale 6) Sold for 35 Keys

https://backpack.tf/profiles/76561198027544408#!/compare/1509321600/1509408000

Note: I took 33 to 48.25 for the Ninja Hood and 37 to 53.5 for the Liquidator's Lid.