Sale 1:

Sold for 15 keys

No outpost

Seller: https://backpack.tf/profiles/76561198121578764#!/compare/1506038400/1506124800

Buyer: https://backpack.tf/profiles/76561198257628196#!/compare/1506038400/1506124800

X = 15

Sale 2:

Sold for Orbiting Fire Milkman + Victory Lap (3)

http://www.tf2outpost.com/trade/29305366 - B/O of 15

Seller: https://backpack.tf/profiles/76561198155320889#!/compare/1501891200/1501977600

Buyer: https://backpack.tf/profiles/76561198121416897#!/compare/1501977600/1502064000

Easily caps, buyers at 12+ on the OF Milk: https://i.imgur.com/on7SCE1.png

X = 15 (Capped by B/O)

Sale 3:

Sold for 13 keys + 10.33 ref

http://www.tf2outpost.com/trade/29352291 - B/O of 14

Seller: https://backpack.tf/profiles/76561198072240925#!/compare/1504396800/1504483200

Buyer: https://backpack.tf/profiles/76561198227232564#!/compare/1504396800/1504483200

X = 13

Sale 4:

Sold with a key for Bubbling Front Runner

No outpost

Seller: https://backpack.tf/profiles/76561198080795417#!/compare/1500249600/1500508800

Buyer: https://backpack.tf/profiles/76561198203753648#!/compare/1500422400/1500681600

Can be used to update the Front Runner

Sale 5:

Bulk for Stormy Dapper Topper

Seller: https://backpack.tf/profiles/76561198072240925#!/compare/1501891200/1501977600

Buyer: https://backpack.tf/profiles/76561198050930436#!/compare/1501977600/1502064000

Sale 6:

Sold with items for Max’s Head

Seller: https://backpack.tf/profiles/76561198050930436#!/compare/1502323200/1502409600

Buyer: https://backpack.tf/profiles/76561198081002938#!/compare/1502323200/1502409600

Sale’s chunky, and would either fall in the range or be lower than buyers. Excluding this sale.

Sale 7:

Bulk for Burning Toy Soldier

Seller: https://backpack.tf/profiles/76561198227232564#!/compare/1504569600/1504656000

Buyer: https://backpack.tf/profiles/76561198361974761#!/compare/1504483200/1504656000

Shouldn’t even be used on the Toy Soldier, as there’s a buyer for 70.

Sellers:

~12.9 keys:

https://i.imgur.com/sHlqWZ7.png - 4 days

13 keys:

https://i.imgur.com/UWLX95l.png - 10 days

https://i.imgur.com/sdE2G2H.png - 12 days

Sales at:

13

15 (2x)

Going with 13-15.