I do not like this range at all

Sale 1

http://www.tf2outpost.com/trade/27232640 Sold for 15 keys

B/O for Festivizer was 15

X = 15

Keys https://gyazo.com/0565c9ee87b9e91e9bdd3a9874b9d541 http://backpack.tf/profiles/76561198069892390?time=1444978800&compare=1444892400

Festivizer http://backpack.tf/item/855348350

Sale 2

http://www.tf2outpost.com/trade/27099186 Sold for Blizz Reggae

Festiv had no trade, presuming offered

X = 20

Reggae http://backpack.tf/item/1666929630

Festiv http://backpack.tf/item/1355205353

Mini for Reggae

http://backpack.tf/vote/id/56614818dea9e9c27a7f76dc 20 keys, using 20

Sale 3 OUTLIER

http://www.tf2outpost.com/trade/27445625 Sold for DBD Escorter

X = 14*0.9

X = 13

Escorter http://backpack.tf/item/2695057780

Festiv http://backpack.tf/item/1355205353

Mini for Escorter

http://backpack.tf/vote/id/56615a55dea9e9bd7a7f7705 14 keys, using 14

Seller

http://www.tf2outpost.com/trade/27371378 Apparently has an offer of 19 keys, making 13 keys an outlier