Not so "Wanted" anymore.

All sales are from the last 30 days

Sale 1:

Sold for 14 keys

Seller: https://backpack.tf/profiles/76561198063481318#!/compare/1514764800/1514851200

Buyer: https://backpack.tf/profiles/76561198238445404#!/compare/1514764800/1514851200

X = 14

Sale 2:

Sold for 13 keys

Seller: https://backpack.tf/profiles/76561198059098316#!/compare/1515283200/1515369600

Buyer: https://backpack.tf/profiles/76561198061103166#!/compare/1515283200/1515369600

X = 13

Sale 3:

Sold with less than 1.5 keys worth for Stormy Storm Attendant (Outdated, quickbuyers at ~13.05)

http://www.tf2outpost.com/trade/29503211 - B/O of 12

Seller: https://backpack.tf/profiles/76561198200270154#!/compare/1514851200/1514937600

Buyer: https://backpack.tf/profiles/76561198397773606#!/compare/1514851200/1514937600

Easily caps.

X = 12 (Capped by B/O)

Sale 4:

Sold for 10 keys + 19 ref the day it became tradable

http://www.tf2outpost.com/trade/29491348 - B/O of 30

Seller: https://backpack.tf/profiles/76561198069580305#!/compare/1514678400/1514764800

Buyer: https://backpack.tf/profiles/76561198063481318#!/compare/1514678400/1514764800

X = 11

Sale 5:

Sold for Blizzardy Storm Tippler's Tricorne + Strange Dead of Night

Seller: https://backpack.tf/profiles/76561198397773606#!/compare/1514937600/1515024000

Buyer: https://backpack.tf/profiles/76561198156886905#!/compare/1514332800/1515024000

Gonna be too high, excluding.

Sale 6:

Sold with another Holy Grail Most Wanted for 16 keys?

Seller: https://backpack.tf/profiles/76561198032732274#!/compare/1515369600/1515456000

Buyer: https://backpack.tf/profiles/76561198379237846#!/compare/1515283200/1515369600

Sale 7:

Bulk for Showstopper Banjo

Seller: https://backpack.tf/profiles/76561198379237846#!/compare/1515801600/1515888000

Buyer: https://backpack.tf/profiles/76561198379237846#!/compare/1515801600/1515888000

Sale 8:

Bulk for Duped Scorching Head Warmer

Seller: https://backpack.tf/profiles/76561198409022488#!/compare/1514937600/1515024000

Buyer: https://backpack.tf/profiles/76561198202477376#!/compare/1514851200/1515024000

Sale 9:

Bulk for something

Seller: https://backpack.tf/profiles/76561198103918688#!/compare/1515196800/1515283200

Buyer: https://backpack.tf/profiles/76561198109741995#!/compare/1515110400/1515283200

Sellers:

~13.8 keys:

https://i.imgur.com/aXd5ASO.png

14 keys:

https://i.imgur.com/EFOsby4.png - 13 days

~14.5 keys:

https://i.imgur.com/M4oaNhE.png - 16 days

16 keys:

https://i.imgur.com/v2pJg1w.png

19 keys:

https://i.imgur.com/xVTm8bx.png - 2 months

Offers:

http://www.tf2outpost.com/trade/29525479 - 4 days

http://www.tf2outpost.com/trade/29523879 - 6 days

Sales at:

11

12

13

14

11 sold pretty quickly. (So did 14, but sellers show that it shouldn't be excluded from the range.) Excluding 11.

Going with 12-14.