Mine sold for 14 keys and it wasn't clean. I'd say 15 keys is a better price. https://imgur.com/a/jmYXF

Another sale:

Sold for 19 Keys, Outlier

https://backpack.tf/profiles/76561198112660684#!/compare/1510272000/1510358400

Added 2 Keys and negligible sweets for a Steaming Le Party Phantom(18 Keys)(16 Keys total)

https://backpack.tf/profiles/76561198089253101#!/compare/1510099200/1510185600

There were two sellers at 15 Keys, but both of their sales are untraceable, so they're not valid. Either way, this would mean that 19's too high, and 13's too low.

16 Keys should be fine here, resuggest at that.