Duck Sauce.

https://backpack.tf/item/3648932005

Sale) Sold + ~3 Keys of Items for a Searing Plasma Trophy Belt (30 Keys)

https://backpack.tf/profiles/76561197996025062#!/compare/1498089600/1498176000 - Seller's Backpack

https://backpack.tf/profiles/76561198081793950#!/compare/1498089600/1498176000 - Buyer's Backpack

30 - 3 = 27 Keys

Trophy Mini

https://backpack.tf/item/205993623

Sale 1) Sold for a Haunted Ghosts Bonk Helm (24.5 Keys) + 5.5 Keys of Items

https://backpack.tf/profiles/76561197987386360#!/compare/1499558400/1499644800 - Buyer's Backpack

24.5 + 5.5 = 30 Keys

Bonk Micro

https://backpack.tf/suggestion/599705b3cf6c7570983258b6 - 24.5 Keys

https://backpack.tf/item/330991136

Sale 2) Sold for 24 Keys

https://backpack.tf/profiles/76561198107520045#!/compare/1499299200/1499385600

https://backpack.tf/item/278181861

Sale 3) Sold + ~11 Keys of Items + 4 Keys for a Specialized Killstreak Australium Rocket Launcher (~34 Keys)

https://backpack.tf/profiles/76561198075197384#!/compare/1493078400/1497225600 - Buyer's Backpack

Low Outlier.

Sale 4) Sold for an Orbiting Planets Blighted Beak (34 Keys) + ~5.5 Keys of Items + Craft #24 Gentleman's Ushanka

https://backpack.tf/profiles/76561198075197384#!/compare/1498176000/1498262400

Beak Micro

https://backpack.tf/suggestion/59965faacf6c757e8576c52b - 34 Keys

Calling 24 low and 42 high. Taking 30 for the Trophy.