https://marketplace.tf/items/202;15;w1;pk300;strange/

May 16, 2019 sold for $43.99 / 1.82 = 24 keys

https://backpack.tf/profiles/76561198045674218#!/compare/1554508800/1554595200

Pro KS S. FN Woodland Warrior Rocket + S. FN Butcher Bird Grenade (4 keys)

Closest mini to Pro KS S. FN Woodland Warrior Rocket is this:

https://backpack.tf/profiles/76561198218497692#!/compare/1551657600/1551744000

No KS S. FN Woodland Warrior Rocket + S. FN Pro KS Black Dahlia Pistol (~16 keys) + ~.5 key item

No KS Woodland Warrior Rocket

https://steamcommunity.com/market/listings/440/Strange%20Woodland%20Warrior%20Rocket%20Launcher%20%28Factory%20New%29

Just from April, taking an average of ~6 keys

Makes the Yeti Minigun around 26 keys