20,000 volts straight to the temples.

https://backpack.tf/item/6287654117

Sale 1) Sold for 16 Keys + Mannrobics (1.15 Keys)

https://backpack.tf/profiles/76561198004383856#!/compare/1510358400/1510531200

16 + 1.15 = 17.15, which rounds to 17 Keys

https://backpack.tf/item/4872043464

Sale 2) Sold for a Kill-a-Watt Towering Pillar of Hats (22.5 Keys)

https://backpack.tf/profiles/76561198132226518#!/compare/1512691200/1512777600

Rounds to 23 Keys

https://backpack.tf/item/4862226214

Sale 3) Sold for 20 Keys

https://backpack.tf/profiles/76561198311911589#!/compare/1511395200/1511481600

https://backpack.tf/item/4862213785

Sale 4) Sold for a Vivid Plasma Respectless Robo-Glove + ~4 Keys of Items

https://backpack.tf/profiles/76561198019370873#!/compare/1510963200/1512259200

http://www.tf2outpost.com/trade/29445399 - Capped by the Buyout of 22 Keys

Sale 5) Sold + ~1 Key of Items for a Blizzardy Storm Modest Metal Pile of Scrap (21 Keys)

https://backpack.tf/profiles/76561198034154143#!/compare/1512172800/1512259200

21 - 1 = 20 Keys

Scrap Mini

https://backpack.tf/suggestion/5a5426cbcf6c75526b00ef47 - 21 Keys

Sale 6) Sold + ~4 Keys of Items for a Starstorm Insomnia Nasty Norsemann (21.5 Keys)

https://backpack.tf/profiles/76561198034154143#!/compare/1512777600/1512950400

21.5 - 4 = 17.5, which rounds to 18 Keys

Sale 7) Sold for 17 Keys + 30 Refined

https://backpack.tf/profiles/76561198015296784#!/compare/1513555200/1513641600

Rounds to 18 Keys

https://backpack.tf/item/4413031420

Sale 8) Sold for 14 Keys + ~2 Keys of Items + ~1 Key of Refined

https://backpack.tf/profiles/76561198155066949#!/compare/1509840000/1509926400

14 + 2 + 1 = 17 Keys

Sale 9) Sold for 17 Keys

https://backpack.tf/profiles/76561198311911589#!/compare/1511654400/1511740800

Sale 10) Sold for 17 Keys

https://backpack.tf/profiles/76561198120551366#!/compare/1512950400/1513036800 - Buyer's Backpack

https://backpack.tf/item/4271549609

Sale 11) Sold for a Nuts and Bolts Janissary Ketche + Nuts and Bolts Magistrate's Mullet + Strange Killer's Kit (2.5 Keys)

https://backpack.tf/profiles/76561198194107098#!/compare/1511481600/1511568000 - Buyer's Backpack

Fits in the range.

Sale 12) Quicksold for 17 Keys

https://backpack.tf/profiles/76561198091914121#!/compare/1511913600/1512000000 - Seller's Backpack

https://backpack.tf/profiles/76561198253042932#!/compare/1511308800/1512000000 - Buyer's Backpack

The Nanobalaclava in the Buyer's Backpack sold for some Keys that were used to buy the Universal Translator.

Sale 13) Sold for 17 Keys

https://backpack.tf/profiles/76561198253042932#!/compare/1512086400/1512345600

https://backpack.tf/item/4240738709

Sale 14) Sold for a '72 Spent Well Spirits + 2 Keys

https://backpack.tf/profiles/76561198291781936#!/compare/1511568000/1511654400

This would be better used to update the Spirits.

Sale 15) Sold for 15 Keys

https://backpack.tf/profiles/76561198079422646#!/compare/1512259200/1512345600

Low Outlier.

https://backpack.tf/item/4203498080

Sale 16) Sold for 18 Keys

https://backpack.tf/profiles/76561198159604288#!/compare/1512518400/1512604800 - Buyer's Backpack

https://backpack.tf/item/4222943003

Sale 17) Sold for 16 Keys + ~1 Key of Items

https://backpack.tf/profiles/76561197998934095#!/compare/1511568000/1511654400

16 + 1 = 17 Keys

Sale 18) Sold for a Circling TF Logo Airdog

https://backpack.tf/profiles/76561198210043095#!/compare/1511654400/1511740800 - Buyer’s Backpack

Fits in the range.

Sale 19) Sold for 16 Keys + ~1 Key of Items

https://backpack.tf/profiles/76561198322031414#!/compare/1513296000/1513382400 - Buyer’s Backpack

16 + 1 = 17 Keys

Sale 20) Sold for 18 Keys

https://backpack.tf/profiles/76561198322031414#!/compare/1515283200/1515456000

https://marketplace.tf/items/30658;5;u96 - 2 Sales at ~21 Keys.