Party like it's 1980-something. I don't know the song.

https://backpack.tf/item/5666886185

Sale 1) Sold for 20 Keys

https://backpack.tf/profiles/76561198157508353#!/compare/1500336000/1500422400

https://backpack.tf/item/1860439895

Sale 2) Sold for 25 Keys

https://backpack.tf/profiles/76561198065110191#!/compare/1499212800/1499299200

Sale 3) Sold for a Steaming Front Runner (15.5 Keys) + Aces Tam (11 Keys)

https://backpack.tf/profiles/76561198258897156#!/compare/1499817600/1499904000

15.5 + 11 = 26.5, which rounds to 27 Keys

Sale 4) Sold for a Smoking Modest Metal Pile of Scrap (25.5 Keys)

https://backpack.tf/profiles/76561198161625387#!/compare/1499904000/1499990400

Rounds to 26 Keys

https://backpack.tf/item/2506613148

Sale 5) Sold for a Specialized Killstreak Australium Grenade Launcher (14 Keys) + Specialized Killstreak Australium Stickybomb Launcher (12 Keys)

https://backpack.tf/profiles/76561198114402400#!/compare/1497052800/1497139200

14 + 12 = 26 Keys

https://backpack.tf/item/2010639776

Sale 6) Sold for a Max's Severed Head (19 Keys at the time of the sale) + ~12 Keys of Items

https://backpack.tf/profiles/76561198096903352#!/compare/1494201600/1494288000

http://www.tf2outpost.com/trade/28909867 - Capped by the Buyout of 30 Keys

Calling 20 Keys low.