Le Train is here

http://backpack.tf/item/747886852

Sale 1) Sold + 6 Keys for a GE Milkman

http://backpack.tf/profiles/76561198097990662#!/compare/1461369600/1461456000

http://www.tf2outpost.com/trade/28100509 - Most likely capped by the buyout of 24 Keys

Sale 2) Sold for a Terror-Watt Towering Pillar of Hats (27 Keys)

http://backpack.tf/profiles/76561198199830590#!/compare/1463529600/1463702400 - Buyer's Backpack

Sale 3) Sold for a Terror-Watt One Man Army (18 Keys) + Strange AWP (~6 Keys) + ~1 Key of Metal

http://backpack.tf/profiles/76561198042562877#!/compare/1465257600/1465344000

18 + 6 + 1 = 25 Keys

Sale 4) Sold for a Blizzardy Storm Big Country (14.5 Keys) + 5 Keys

http://backpack.tf/profiles/76561198277696956#!/compare/1465776000/1465862400

14.5 + 5 = 19.5, which rounds to 20 Keys