Just a little bit further!

http://backpack.tf/item/2236727315

Sale 1) Sold for 25 Keys

http://backpack.tf/profiles/76561198042938501#!/compare/1472601600/1472688000

Sale 2) Sold for a Blizzardy Storm Prancer's Pride + Blizzardy Storm Doctor's Sack

http://backpack.tf/profiles/76561198049793971#!/compare/1469145600/1469232000

http://www.tf2outpost.com/trade/28416330 - Capped by the Buyout of 25 Keys

Sale 3) Sold for a Cloud 9 Boron Beanie + Dead Presidents Black Watch

http://backpack.tf/profiles/76561198081642082#!/compare/1471910400/1471996800

http://www.tf2outpost.com/trade/28440343 - Capped by the Buyout of 25 Keys

Sale 4) Sold + ~0.3 Keys of Items for a Miami Nights Connoisseur's Cap (18.5 Keys)

http://backpack.tf/profiles/76561198300504283#!/compare/1471996800/1472083200

18.5 - 0.3 = 18 Keys

Sale 5) Sold for an Orbiting Planets Front Runner + Strange Hatypus (2 Keys)

http://backpack.tf/profiles/76561197994183154#!/compare/1468108800/1468627200

Close to 18 Keys. Supports the low end.