Sale 1:

Sold to STN for 17 keys + ~1 key in metal

https://backpack.tf/profiles/76561198141685007#!/compare/1736035200/1736121600

https://backpack.tf/profiles/76561199581722058#!/compare/1736035200/1736121600

https://backpack.tf/item/11334281707

= 18 keys

Sale 2:

Untraceable

https://backpack.tf/profiles/76561199581722058#!/compare/1738886400/1738972800

Buyer not found

https://backpack.tf/item/11334281707

https://stntrading.eu/item/tf2/Unusual+Searing+Plasma+Vampire+Vanquisher

https://i.imgur.com/ojtUSDI.png - given STN’s page on the item, it most likely sold for 18 keys + 9 ref

Sale 3:

Sold for Cosmic Constellations Bulb Bonnet

https://backpack.tf/profiles/76561199028814813#!/compare/1735344000/1735689600

https://backpack.tf/profiles/76561198141685007#!/compare/1735430400/1735516800

https://backpack.tf/item/11334281707

Using there.

Sellers/Buyers:

https://i.imgur.com/n16Xgpw.png

https://backpack.tf/item/8122703372 - $49.99, marketplace

Highest buyer at ~14.6 keys

Sale at 18, another likely sale at 18. Third sale if used here would be ~14 keys.

Taking 18 flat.