Magic is Spooky.

https://backpack.tf/item/4180602880

Sale 1) Sold for a Vivid Plasma Brain-Warming Wear (17.5 Keys) + 2 Keys + <0.5 Keys of Items

https://backpack.tf/profiles/76561198121660651#!/compare/1499644800/1499731200

http://www.tf2outpost.com/trade/29268465 - Capped by the Buyout of 19 Keys

Sale 2) Sold for 14 Keys

https://backpack.tf/profiles/76561198130503112#!/compare/1501372800/1501459200 - Buyer's Backpack

Low Outlier because of the multiple quickbuyers at 14 Keys and higher (shown at the bottom).

Sale 3) Sold for 15 Keys + 2 Refined

https://backpack.tf/profiles/76561198130503112#!/compare/1502668800/1502755200

Low Outlier because of the Buyer listed below at 15 Keys.

Credits to Mindacos for this sale.

Sale 4) Sold for 16 Keys

https://backpack.tf/profiles/76561198048008254#!/compare/1504569600/1504656000

https://marketplace.tf/items/1112;5;u3013 - Marketplace sale at $53. Keys were ~$2.05 at the time. 53 / 2.05 = ~26 Keys. This is a high Outlier.