It's been a day. Credits to Beaser for Sale 2 and the Coupe Mini and Scrub for Sale 3.

http://backpack.tf/item/3282021439

Sale 1) Sold + Strange Toowoomba Tunic (1 Key) for a DBD Nano (21.5 Keys)

http://backpack.tf/profiles/76561198135031569#!/compare/1480118400/1480204800

21.5 - 1 = 20.5, which rounds to 21 Keys

Sale 2) Sold for an Eerie Pugilist (13 Keys) + DBD Coupe (12 Keys) + 1 Key

http://backpack.tf/profiles/76561198268349205#!/compare/1482192000/1482278400 - Buyer's Backpack

13 + 12 + 1 = 26 Keys

Coupe Mini

http://imgur.com/gAfNNm3 - Unsold for 3 Months at 12 Keys

Pugilist Mini

http://backpack.tf/profiles/76561198024302996#!/compare/1482537600/1482710400 - Sold for a Planets Drill Hat (13 Keys)

Drill Hat Micro

http://backpack.tf/profiles/76561198014728963#!/compare/1482796800/1482883200 - Sold for 13 Keys

Sale 3) Sold for a Hellish Inferno Spent Well Spirits (24 Keys)

http://backpack.tf/profiles/76561198243530442#!/compare/1483056000/1483142400