This was a doozy.

https://backpack.tf/item/5541682946

Sale 1) Sold for a Midnight Whirlwind Party Trick

https://backpack.tf/profiles/76561198162282453#!/compare/1499904000/1499990400

There's no good Mini for the Party Trick, just a quicksell for 17 Keys. This can be used to price that.

Sale 2) Sold for a Neutron Star Caribbean Conqueror

https://backpack.tf/profiles/76561198111143900#!/compare/1500422400/1500508800

Seeing as the Conqueror is not priced, this sale can be used to price that.

https://backpack.tf/item/5569173568

Sale 3) Sold + 1 Key + <0.5 Keys of Refined and Items for a Dead Presidents Tough Stuff Muffs (25 Keys)

https://backpack.tf/profiles/76561197997810328#!/compare/1499731200/1499817600

25 - 1 - <0.5 = >23.5, which rounds to 24 Keys

Sale 4) Sold for an Aces High Employee of the Mmmph (16.5 Keys)

https://backpack.tf/profiles/76561198042497833#!/compare/1499904000/1499990400 - Buyer's Backpack

Rounds to 17 Keys

Sale 5) Sold for a '72 Soldier's Requiem (30 Keys)

https://backpack.tf/profiles/76561198042497833#!/compare/1503014400/1503100800

http://www.tf2outpost.com/trade/29279022 - Capped by the Buyout of 21 Keys

Calling 24 high because of this 26 Day Seller at 24 Keys: http://imgur.com/a/jRvHf