A merry group.

http://backpack.tf/item/4978267481

Sale 1) Sold for a Neutron Star Lil' Bitey (38 Keys) + 3 Keys + ~2 Keys of Items

http://backpack.tf/profiles/76561198043992035#!/compare/1486512000/1486598400

38 + 3 + 2 = 43 Keys

http://backpack.tf/item/4955240010

Sale 2) Sold for a Circling Hearts Scotch Bonnet (24 Keys) + Australium Grenade Launcher (15 Keys)

http://backpack.tf/profiles/76561198173989455#!/compare/1490659200/1490745600 - Buyer's Backpack

24 + 15 = 39 Keys

http://backpack.tf/item/5375536433

Sale 3) Sold for a Molten Mallard Towering Titanium Pillar of Hats (40.5 Keys) + ~1.5 Keys of Items

http://backpack.tf/profiles/76561198002757046#!/compare/1487548800/1487635200

40.5 + 1.5 = 42 Keys

Pillar Mini

http://backpack.tf/suggestion/58eedbadc440456362508304 - 40.5 Keys

I rounded the sale to 41 to make a suggestion, but I'll treat this sale as 40.5 Keys here.

Sale 4) Sold + Green Energy Bootleg Base Metal Billycock for a Vivid Plasma Towering Pillar of Hats + Smoking Soldered Sensei

http://backpack.tf/profiles/76561198144352975#!/compare/1487030400/1487116800

High Outlier

Sale 5) Sold for a Steaming Airdog (15 Keys) + 13 Keys + Steaming Broadband Bonnet (10 Keys)

http://backpack.tf/profiles/76561198143206871#!/compare/1488931200/1489017600

15 + 13 + 10 = 38 Keys

Airdog Mini

http://imgur.com/a/vUCoV - Taking 15 Keys