Sale 1:

Sold for Max’s Head (~18 at the time)

No outpost

Seller: https://backpack.tf/profiles/76561198272453633#!/compare/1506211200/1506384000

Buyer: https://backpack.tf/profiles/76561198132388669#!/compare/1506297600/1506384000

X = 18

Sale 2:

Sold for Terror-Watt Slick Cut (Mini at 16 below)

Seller: https://backpack.tf/profiles/76561198304156697#!/compare/1505001600/1505088000

Buyer: https://backpack.tf/profiles/76561198167163006#!/compare/1505001600/1505088000

X = 16

Sale 3:

Sold for Skullcracker Unusualifier (~18)

No outpost

Seller: https://backpack.tf/profiles/76561198086793593#!/compare/1509235200/1509321600

Buyer: https://backpack.tf/profiles/76561198293295694#!/compare/1508976000/1509321600

Probably better to use this sale as support more than anything else.

Terror-Watt Slick Mini:

Sold for 16 keys?

Seller: https://backpack.tf/profiles/76561198035796132#!/compare/1506470400/1506556800

Buyer: https://backpack.tf/profiles/76561198110526996#!/compare/1506211200/1506729600

I suspect that the only reason the ID’s don’t match is because the new owner adjusted the positioning of the effect, which creates a new ID the first time someone does it, before their backpack was scanned. Didn’t want to make a suggestion out of this just in case I am wrong.

Sellers:

14.5 keys:

https://i.imgur.com/uK42rzn.png - 10 days

19 keys:

https://i.imgur.com/2sDzffX.png - 8 days

20 keys:

https://i.imgur.com/9bfNFiX.png - 8 days

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

Offers:

http://www.tf2outpost.com/trade/29409330 - 1 month

Sales at:

16

18 (2x)

Seller at 14.5, rounding down given that keys appear to be raising, making this fall under 14.5. Would also create a neat whole number for the median value.

Going with 14-18.