Why did they retire this thing, anyway? Were they tired of making money off it?

Sold for 13 Keys

http://backpack.tf/profiles/76561198138292052#!/compare/1481500800/1481673600

Sold for an Australium Spec KS Flame Thrower(~16 Keys)

http://backpack.tf/profiles/76561198125791160#!/compare/1483228800/1483315200

Sold with ~2 Keys in Sweets for a Subatomic Head Full of Hot Air(18 Keys)(16 Keys total)

http://backpack.tf/profiles/76561198272871035#!/compare/1484092800/1484438400

Sold for a Stormy Storm Crocleather Slouch(18 Keys, Outlier)

http://backpack.tf/profiles/76561198257292274#!/compare/1484438400/1484697600

Sold with ~7 Keys in Sweets for an Australium Pro KS Stickybomb Launcher(~21 Keys)(14 Keys total)

http://backpack.tf/profiles/76561198082677089#!/compare/1487721600/1487808000

http://backpack.tf/profiles/76561198179506738#!/compare/1487721600/1487808000

Sold for an Australium Spec KS Tomislav(~13 Keys)

http://backpack.tf/profiles/76561198087757951#!/compare/1487635200/1487808000

Sold for a Steaming Brigade Helm(13.5 Keys, round to 14) and 1 Key(15 Keys total)

http://backpack.tf/profiles/76561198085966081#!/compare/1485302400/1485388800

Sold for a Steaming Brigade Helm(13.5 Keys, round to 14)

http://backpack.tf/profiles/76561198108360671#!/compare/1485475200/1485648000

http://backpack.tf/item/1128916214

Sold for 13 Keys

http://backpack.tf/profiles/76561198297529937#!/compare/1486771200/1486857600

13-16.

Credits to Mindacos for the suggestion. He found the proof, I'm just posting it.