Sale 1:

Sold for Aussie Stickybomb Launcher (17 at the time)

No outpost

Seller: http://backpack.tf/profiles/76561198123097664#!/compare/1463616000/1463702400

Buyer: http://backpack.tf/profiles/76561198116100132#!/compare/1463702400/1463961600

X = 17

Sale 2:

Sold for Pro. KS Aussie Frontier Justice (~14 at the time) + 2 keys + ~1 key in items

http://www.tf2outpost.com/trade/27945790 - Offers

Seller: http://backpack.tf/profiles/76561198148577987#!/compare/1459987200/1460073600

Buyer: http://backpack.tf/profiles/76561198054882519#!/compare/1459987200/1460073600

X = 17

Pro. KS Aussie Frontier Justice:

http://puu.sh/oyDtu/60eb5f18a6.jpg

http://puu.sh/oyDun/27725bceaf.jpg

I had these screenshots saved for a while, good thing I never delete them :P

Sale 3:

Sold for 16 keys + ~1 key in items

http://www.tf2outpost.com/trade/28072216 - No B/O, Buyer offers here

Seller: http://backpack.tf/profiles/76561198054882519#!/compare/1460678400/1460764800

Buyer: http://backpack.tf/profiles/76561198097205825#!/compare/1459036800/1462406400

X = 17

Sale 4:

Sold for 16 keys

Seller: http://backpack.tf/profiles/76561198002757046#!/compare/1460332800/1460419200

Buyer: http://backpack.tf/profiles/76561198219167124#!/compare/1460332800/1460505600

Key histories don’t match on backpack, but:

http://puu.sh/pAogT/99efb7347a.png - These keys, according to outpost, came from the buyer

http://www.tf2outpost.com/item/440,4733825556 (one of the keys)

X = 16

Sale 5:

Sold for 15 keys in less than a day

http://www.tf2outpost.com/trade/28171066 - B/O of 16, looks to have sold without a bump

Seller: http://backpack.tf/profiles/76561198180884747#!/compare/1463270400/1463616000

Buyer: http://backpack.tf/profiles/76561198159344215#!/compare/1463184000/1463443200

X = 15

Sale 6:

Sold for Bubbling Physician’s Protector

Seller: http://backpack.tf/profiles/76561198116100132#!/compare/1464220800/1464566400

Buyer: http://backpack.tf/profiles/76561198084153073#!/compare/1464220800/1464393600

Should definitely be used to price the Protector

Sale 7:

Sold with 10 keys for DBD Milkman

Seller: http://backpack.tf/profiles/76561198097205825#!/compare/1462838400/1466467200

Buyer: http://backpack.tf/profiles/76561198180884747#!/compare/1463011200/1463270400

Should be used to update the DBD Milkman

Sale 8:

Sold with ~1 key in items for Steaming Private Eye

Seller: http://backpack.tf/profiles/76561198152822390#!/compare/1464393600/1464480000

Buyer: http://backpack.tf/profiles/76561198102764426#!/compare/1464480000/1464566400

Should be used to update the Private Eye

Sale 9:

Sold with Strange Lime Thermal Tracker for Kill-a-Watt Rubber Glove

Seller: http://backpack.tf/profiles/76561198150447896#!/compare/1460073600/1460160000

Buyer: http://backpack.tf/profiles/76561198002757046#!/compare/1460073600/1460160000

Should probably be used to update the Rubber Glove

Sellers:

17 keys:

http://www.tf2outpost.com/trade/28259445 - 6 days

18 keys:

http://www.tf2outpost.com/trade/28266334 - 2 days

20 keys:

http://puu.sh/pAq4T/e94028253d.png

Sales at:

15

16

17

17

17

Sale at 15 happened too quickly, and should be excluded from the range.

Going with 16-17