Sale 1:

Sold for Terror-Watt Milkman (Suggestion at 14) + cheap skin

No outpost

Seller: https://backpack.tf/profiles/76561198163542918#!/compare/1504396800/1504483200

Buyer: https://backpack.tf/profiles/76561198121416897#!/compare/1504483200/1504569600

X = 14

Sale 2:

Sold for 12 keys + 10 ref

http://www.tf2outpost.com/trade/29387932 - B/O of 15

Seller: https://backpack.tf/profiles/76561197982879578#!/compare/1506988800/1507161600

Buyer: https://backpack.tf/profiles/76561198163912348#!/compare/1505001600/1507161600

X = 12

Sale 3:

Sold with some ref for 11 keys in ~2 days

http://www.tf2outpost.com/trade/29371726 - B/O of 12

Seller: https://backpack.tf/profiles/76561198053747026#!/compare/1505606400/1505692800

Buyer: https://backpack.tf/profiles/76561198128091635#!/compare/1505606400/1505692800

X = 11

Sale 4:

Sold, to my buy order, for 10 keys + 19 ref

Seller: https://backpack.tf/profiles/76561198068351675#!/compare/1507507200/1507680000

Buyer: https://backpack.tf/profiles/76561198021055079#!/compare/1507593600/1507680000

X = 11

Sale 5:

Sold with ~9 keys in pure/items for Vivid Plasma Baker Boy

Seller: https://backpack.tf/profiles/76561198128091635#!/compare/1506729600/1506816000

Buyer: https://backpack.tf/profiles/76561197982879578#!/compare/1506556800/1506816000

Should be used on the Vivid baker.

Sale 6:

Bulk for PE Brain-Warming Wear

Seller: https://backpack.tf/profiles/76561198098262596#!/compare/1507420800/1507507200

Buyer: https://backpack.tf/profiles/76561198121929211#!/compare/1507420800/1507507200

Sale 7:

Bulk for Aces Tipped Lid

Seller: https://backpack.tf/profiles/76561198121929211#!/compare/1507507200/1507680000

Buyer: https://backpack.tf/profiles/76561198068351675#!/compare/1507507200/1507680000

Terror-Watt Milkman:

https://backpack.tf/suggestion/59df7fefcf6c7532db3db524

Sellers:

~13.4 keys:

https://i.imgur.com/mtEJvaZ.png - 2 days

14 keys:

https://i.imgur.com/PvSTU8G.png - 1 day (it is I, Jarool)

Sales at:

11 (2x)

12

14

Sales at 11 went to a buy order/quicksold. Excluding 11.

Going with 12-14.