Sale 1:

Sold for 7 keys

Seller: https://backpack.tf/profiles/76561198167436981#!/compare/1522886400/1522972800

Buyer: https://backpack.tf/profiles/76561198397510168#!/compare/1522800000/1522972800

X = 7

Sale 2:

Bot.tf sale at 6 keys + 25 ref

https://i.imgur.com/l144Svx.png

Couldn’t find the sale myself

X = 7

Sale 3:

Sold for 6 keys + 15 ref

Seller: https://backpack.tf/profiles/76561198091502579#!/compare/1523145600/1523232000

Buyer: https://backpack.tf/profiles/76561198230109280#!/compare/1523145600/1523232000

X = 6.5

Sale 4:

Nothing matches, but I’m certain it sold for 6 keys + 15 ref

Seller: https://backpack.tf/profiles/76561198062613620#!/compare/1522627200/1522713600

Buyer: https://backpack.tf/profiles/76561198126171688#!/compare/1520467200/1523145600

X = 6.5

Sale 5:

Sold for 6 keys + 5 ref

Seller: https://backpack.tf/profiles/76561198289037877#!/compare/1522713600/1522886400

Buyer: https://backpack.tf/profiles/76561198062613620#!/compare/1522627200/1522713600

X = 6

Sale 6:

Sold for 6 keys

Seller: https://backpack.tf/profiles/76561198048008254#!/compare/1521590400/1521676800

Buyer: https://backpack.tf/profiles/76561198047362068#!/compare/1521158400/1521763200

X = 6

Sale 7:

Sold with a key for Mega Strike Jumping Jack

Seller: https://backpack.tf/profiles/76561198005121419#!/compare/1522540800/1522627200

Buyer: https://backpack.tf/profiles/76561198043936328#!/compare/1522540800/1522627200

Better off being used on Jack.

Sale 8:

Sold for Orbiting Planets Puffy Polar Cap

No outpost

Seller: https://backpack.tf/profiles/76561198397510168#!/compare/1522972800/1523059200

Buyer: https://backpack.tf/profiles/76561198278152573#!/compare/1522972800/1523059200

Seems pretty high, excluding.

Sellers:

11 keys:

http://www.tf2outpost.com/trade/29612848

13 keys:

https://i.imgur.com/aQ6nSiu.png

https://backpack.tf/item/4974506762

30 keys:

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

https://backpack.tf/item/6298939803

https://i.imgur.com/f0xglxZ.png

https://backpack.tf/item/4991541642

Sales at:

6 (2x)

6.5 (2x)

7 (2x)

Buyer at 6 in the classifieds is not buying this effect. Safe to leave 6 in.

Going with 6-7.