Sale 1:

Sold for Stormy Storm Prussian Pickelhaube (Suggestion at 16)

No outpost

Seller: https://backpack.tf/profiles/76561198145460851#!/compare/1496793600/1498867200

Buyer: https://backpack.tf/profiles/76561198387130648#!/compare/1496793600/1496966400

X = 16

Sale 2:

Sold for 15 keys (ID’s match)

http://www.tf2outpost.com/trade/28847894 - B/O of 15

Seller: https://backpack.tf/profiles/76561197990986202#!/compare/1494720000/1494806400

Buyer: https://backpack.tf/profiles/76561198078474477#!/compare/1494633600/1494806400

X = 15

Sale 3:

Sold for Stormy Storm Medic’s Mountain Cap (Suggestion at 15)

http://www.tf2outpost.com/trade/29250853 - B/O of 20

Seller: https://backpack.tf/profiles/76561198061314928#!/compare/1498953600/1499040000

Buyer: https://backpack.tf/profiles/76561198074289192#!/compare/1498867200/1499040000

X = 15

Sale 4:

Sold for Stormy Storm Grenadier’s Softcap (15)

http://www.tf2outpost.com/trade/29201229 - B/O of 15

Seller: https://backpack.tf/profiles/76561198147243794#!/compare/1495756800/1495843200

Buyer: https://backpack.tf/profiles/76561198125791160#!/compare/1495756800/1495843200

X = 15

Sale 5:

Bulk for Purple Confetti Blighted Beak

Seller: https://backpack.tf/profiles/76561198185387026#!/compare/1492646400/1492732800

Buyer: https://backpack.tf/profiles/76561198066195760#!/compare/1492646400/1492732800

Stormy Pickel Suggestion:

https://backpack.tf/suggestion/596e4f36cf6c750911182805

Stormy Mountain Cap Suggestion:

https://backpack.tf/suggestion/596e46c5cf6c7575676d2a2c

Sellers:

17 keys:

http://i.imgur.com/eEr4DRZ.png

19 keys:

http://i.imgur.com/WTKeCGM.png - 2 months

http://i.imgur.com/T6qyWqT.png - 5 months

20 keys:

http://i.imgur.com/Mv16cbH.jpg - 3 months

Sales at:

15 (3x)

16

Going with 15-16.