Sale 1:

Sold for Orbiting Planets Blast Defense (Suggestion at 10)

No outpost

Seller: https://backpack.tf/profiles/76561198125082062#!/compare/1519344000/1519430400

Buyer: https://backpack.tf/profiles/76561198346506937#!/compare/1519344000/1519430400

X = 10

Sale 2:

Sold for 8 keys

Seller: https://backpack.tf/profiles/76561198301836632#!/compare/1518912000/1518998400

Buyer: https://backpack.tf/profiles/76561198166757198#!/compare/1504828800/1522540800

X = 8

Sale 3:

Sold with Festivizer (~1) for Nuts n’ Bolts Berliner’s Bucket Helm (Mini at ~8.75 below)

Seller: https://backpack.tf/profiles/76561198129995083#!/compare/1517875200/1517961600

Buyer: https://backpack.tf/profiles/76561198050272426#!/compare/1517875200/1517961600

X = 8

Sale 4:

Sold for 5 keys + 12 ref

Seller: https://backpack.tf/profiles/76561198048851745#!/compare/1520640000/1520726400

Buyer: https://backpack.tf/profiles/76561198354113551#!/compare/1520726400/1520812800

X = 5.5

Sale 5:

Sold with a cosmetic for Midnight Whirlwind Fubar Fanfare

Seller: https://backpack.tf/profiles/76561198256924017#!/compare/1518912000/1519516800

Buyer: https://backpack.tf/profiles/76561197994697258#!/compare/1519430400/1519516800

Can be used on the Whirlwind Fubar.

Sale 6:

Bulk for Voltaic Hat Protector UT

Seller: https://backpack.tf/profiles/76561198396115136#!/compare/1518912000/1518998400

Buyer: https://backpack.tf/profiles/76561198173389367#!/compare/1518912000/1518998400

Planets Blast Defense:

https://backpack.tf/suggestion/5ac44bdecf6c753e9a309ff1

Nuts Berliner Mini:

Sale 1:

Nothing matches, but I can guarantee that it sold for 9 keys

Seller: https://backpack.tf/profiles/76561198305492646#!/compare/1518652800/1518739200

Buyer: https://backpack.tf/profiles/76561198369697018#!/compare/1518048000/1519603200

Sale 2:

(Currently) untraceable bot.tf sale at ~8.5 keys

https://i.imgur.com/yuYH4DS.png

Sellers:

8 keys:

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

https://backpack.tf/item/6629673195

10 keys:

https://i.imgur.com/4HXqWfl.png

https://backpack.tf/item/6542400269

13 keys:

https://i.imgur.com/uxc8nAn.png

https://backpack.tf/item/6492076227

24 keys:

https://i.imgur.com/R9HpIFz.png

https://backpack.tf/item/5161438079

25 keys:

https://i.imgur.com/qIjDdv4.png

https://backpack.tf/item/4966132263

Offers:

http://www.tf2outpost.com/trade/29606826

http://www.tf2outpost.com/trade/29594116

SCM:

https://i.imgur.com/1ZGQb3V.png

$22.71 (~9.19 keys)

$24.87 (~10.07 keys)

$28.75 (~11.64 keys)

$51.65 (~20.91 keys)

$69.82 (~28.27 keys)

Sales at:

5.5

8 (2x)

10

Gonna exclude 10, given the cheaper sellers.

Will keep 5.5 in the range, as it took 5 days to sell, and if sale 5 were used here, it would end up being around that value too, given the sellers on the Whirlwind Fubar.

Going with 5.5-8.