Sale 1:

Sold for Australium Grenade Launcher (13)

http://www.tf2outpost.com/trade/29382609 - B/O of 11

Seller: https://backpack.tf/profiles/76561198090606907#!/compare/1506470400/1506556800

Buyer: https://backpack.tf/profiles/76561198061608745#!/compare/1506470400/1506556800

X = 11 (Capped by B/O)

Sale 2:

Sold for 10 keys

No outpost

Seller: https://backpack.tf/profiles/76561198344933095#!/compare/1503705600/1503792000

Buyer: https://backpack.tf/profiles/76561198090950070#!/compare/1503705600/1503792000

X = 10

Sale 3:

Sold for 10 keys + 9.66 ref

No outpost

Seller: https://backpack.tf/profiles/76561198042938501#!/compare/1502064000/1502150400

Buyer: https://backpack.tf/profiles/76561198035714317#!/compare/1502064000/1502150400

X = 10

Sale 4:

Sold for 9 keys to a quickbuyer

No outpost

Seller: https://backpack.tf/profiles/76561198379152151#!/compare/1501891200/1501977600

Buyer: https://backpack.tf/profiles/76561198042938501#!/compare/1501804800/1501891200

X = 9

Sale 5:

Sold for a bunch of items

No outpost

Seller: https://backpack.tf/profiles/76561198019768560#!/compare/1506211200/1506297600

Buyer: https://backpack.tf/profiles/76561198189486375#!/compare/1505865600/1506211200

Sale 6:

Bulk for DBD DCO

Seller: https://backpack.tf/profiles/76561198149175706#!/compare/1503964800/1504051200

Buyer: https://backpack.tf/profiles/76561198164036774#!/compare/1503792000/1504051200

Sale 7:

Bulk quicksell for 18 keys

Seller: https://backpack.tf/profiles/76561198164036774#!/compare/1503792000/1504051200

Buyer: https://backpack.tf/profiles/76561198110993295#!/compare/1503964800/1504051200

Sale 8:

Bulk for Steaming TC + Pro. ks Ham

Seller: https://backpack.tf/profiles/76561198110993295#!/compare/1504828800/1504915200

Buyer: https://backpack.tf/profiles/76561198246917494#!/compare/1504828800/1504915200

Sale 9:

Bulk for Misty Blighted Beak

Seller: https://backpack.tf/profiles/76561198041902665#!/compare/1505433600/1505520000

Buyer: https://backpack.tf/profiles/76561198120467518#!/compare/1505347200/1505520000

Sale 10:

no

Seller: https://backpack.tf/profiles/76561198120467518#!/compare/1507075200/1507161600

Buyer: https://backpack.tf/profiles/76561198147734542#!/compare/1507075200/1507161600

no

Sellers:

10 keys: (read notes)

https://i.imgur.com/kvykBuc.png - 4 days

12 keys:

https://i.imgur.com/19O6VYB.png - 6 months

Offers:

http://www.tf2outpost.com/trade/29312093 - 2 months, was offered 9

Sales at:

9

10 (2x)

11

9 sold to a quickbuyer. Excluding 9.

Going with 10-11.