Sale 1:

Sold for 20 keys

Seller: https://backpack.tf/profiles/76561198011321852#!/compare/1506124800/1506211200

Buyer: https://backpack.tf/profiles/76561198292080684#!/compare/1506211200/1506556800

X = 20

Sale 2:

Sold for 18 keys

Seller: https://backpack.tf/profiles/76561198074924284#!/compare/1509667200/1509753600

Buyer: https://backpack.tf/profiles/76561198129985922#!/compare/1509753600/1509840000

X = 18

Sale 3:

Sold with slightly less than 4 keys in items for Disco Beat Down Connoisseur’s Cap (20.5)

No outpost

Seller: https://backpack.tf/profiles/76561198205968628#!/compare/1506643200/1506729600

Buyer: https://backpack.tf/profiles/76561198078131641#!/compare/1506384000/1506816000

X = 17

Sale 4:

Sold for 16 keys + 17.11 ref

Seller: https://backpack.tf/profiles/76561198053747026#!/compare/1509321600/1509408000

Buyer: https://backpack.tf/profiles/76561198156293584#!/compare/1509408000/1509494400

X = 17

Sale 5:

Sold for 15 keys (Buyer’s compare link)

Seller: https://backpack.tf/profiles/76561198304138933#!/compare/1509235200/1509321600

Buyer: https://backpack.tf/profiles/76561198121924585#!/compare/1509321600/1509408000

X = 15

Sale 6:

Sold for 14 keys + 15 ref

Seller: https://backpack.tf/profiles/76561198349886701#!/compare/1508371200/1508457600

Buyer: https://backpack.tf/profiles/76561198149428528#!/compare/1508457600/1508630400

X = 14

Sale 7:

Bulk for Cloud 9 Human Cannonball

Seller: https://backpack.tf/profiles/76561198114724512#!/compare/1506038400/1506124800

Buyer: https://backpack.tf/profiles/76561198061489334#!/compare/1506038400/1506124800

Sale 8:

Bulk for Orbiting Fire Muffs

Seller: https://backpack.tf/profiles/76561198334357092#!/compare/1506729600/1506816000

Buyer: https://backpack.tf/profiles/76561198121929211#!/compare/1506729600/1506816000

Sale 9:

Sold for Strange Neutron Star Spirit of the Bombing Past

Seller: https://backpack.tf/profiles/76561198173810519#!/compare/1506556800/1506643200

Buyer: https://backpack.tf/profiles/76561198110622625#!/compare/1506556800/1506643200

Should be used on the Spirit.

Sale 10:

Sold with 2 keys for Bubbling Allbrero

Seller: https://backpack.tf/profiles/76561198110622625#!/compare/1506816000/1506902400

Buyer: https://backpack.tf/profiles/76561198251704884#!/compare/1506729600/1506902400

Can be used on the Allbrero.

Sale 11:

Sold for Vivid Plasma Berliner’s Bucket Helm

http://www.tf2outpost.com/trade/29377679 - Deleted B/O

Seller: https://backpack.tf/profiles/76561198061489334#!/compare/1506038400/1506124800

Buyer: https://backpack.tf/profiles/76561198334357092#!/compare/1505952000/1506124800

Can be used on the Bucket.

Sale 12:

Sold for Infernal Smoke Spent Well Spirits

Seller: https://backpack.tf/profiles/76561198078131641#!/compare/1510963200/1511049600

Buyer: https://backpack.tf/profiles/76561198400221373#!/compare/1510963200/1511049600

Should be used on the taunt.

Sellers:

~14.3 keys:

https://i.imgur.com/boSkzxj.png - 9 days

~14.9 keys:

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

Sales at:

14

15

17 (2x)

18

20

Going with 14-20.