Skyscreamer.

https://backpack.tf/item/4906365280

Sale 1) Sold for 32 Keys

https://backpack.tf/profiles/76561197989166398#!/compare/1506124800/1506211200

Sale 2) Sold for a Power Surge Tyrantium Helmet

https://backpack.tf/profiles/76561198243350308#!/compare/1506470400/1506643200

This sale would probably better be used to price the Tyrantium because it was last priced 2 Years ago.

Sale 3) Sold + Steaming Big Country for a Phosphorous Prince Tavish's Crown + 10 Keys

https://backpack.tf/profiles/76561198375289388#!/compare/1509321600/1509580800

http://www.tf2outpost.com/trade/29388571 - Capped by the Buyout of 45 Keys

Crown Mini

Sold for a Circling Peace Sign Conquistador + Strange Orbiting Fire Scotsman's Stove Pipe + Smoking Brain-Warming Wear + Bubbling Helmet Without a Home

https://backpack.tf/profiles/76561198087172601#!/compare/1507680000/1507766400

https://backpack.tf/profiles/76561198073070572#!/compare/1507766400/1507852800 - Sold for a Death at Dusk Vintage Merryweather + Bubbling Baker

https://backpack.tf/profiles/76561198129402515#!/compare/1508025600/1508112000 - Sold for a Haunted Ghosts YWN (44.5 Keys) + 2 Keys

The first sale is ~50 Keys, the second is ~50 Keys, and the third is ~47 Keys.

Overall, this averages the Crown to a value higher than 46 Keys, so the 45 Key Buyout cap applies.