Sale 1:

Sold for 16 keys

http://www.tf2outpost.com/trade/28792628 - B/O of 16

Seller: http://backpack.tf/profiles/76561198021055079#!/compare/1487894400/1487980800

Buyer: http://backpack.tf/profiles/76561198150101707#!/compare/1487980800/1488067200

Looks like they sold it to scrap.tf before their backpack got scanned :/

X = 16

Sale 2:

Sold for 14 keys

No outpost

Seller: http://backpack.tf/profiles/76561198018528305#!/compare/1485475200/1485561600

Buyer: http://backpack.tf/profiles/76561198253177889#!/compare/1485475200/1485561600

X = 14

Sale 3:

Sold in ~1 day for 13 keys

No outpost

Seller: http://backpack.tf/profiles/76561198259050137#!/compare/1487116800/1487203200

Buyer: http://backpack.tf/profiles/76561198201384547#!/compare/1487116800/1487203200

X = 13

Sale 4:

Sold for Pro. KS Aussie Axtinguisher (7) + 5 keys in ~2 days

http://www.tf2outpost.com/trade/28775727 - Deleted B/O

Seller: http://backpack.tf/profiles/76561198120672630#!/compare/1486944000/1487030400

Buyer: http://backpack.tf/profiles/76561198259050137#!/compare/1486944000/1487030400

X = 12

Sale 5:

Sold with <5 keys in taunts for Tesla Coil Wide-Brimmed Bandito (16.5)

http://www.tf2outpost.com/trade/28782762 - B/O of 12

Seller: http://backpack.tf/profiles/76561198125626562#!/compare/1487116800/1487203200

Buyer: http://backpack.tf/profiles/76561198015384426#!/compare/1487116800/1487203200

X = 12

Sale 6:

Sold with Strange Spec. KS AWPer Hand (8) for Australium Knife (18 at the time)

No outpost

Seller: http://backpack.tf/profiles/76561198201384547#!/compare/1487203200/1487289600

Buyer: http://backpack.tf/profiles/76561198021055079#!/compare/1487203200/1487289600

http://imgur.com/a/wJPn9

X = 10

Sale 7:

Sold for Smoking Bonk Helm + 1 key

No outpost

Seller: http://backpack.tf/profiles/76561198272242576#!/compare/1487116800/1487203200

Buyer: http://backpack.tf/profiles/76561198136744617#!/compare/1487203200/1487289600

This’ll most likely end up fitting in the range.

Sale 8:

Bulk for Tesla Coil Brotherhood of Arms

Seller: http://backpack.tf/profiles/76561198116132079#!/compare/1485648000/1486857600

Buyer: http://backpack.tf/profiles/76561198120672630#!/compare/1486771200/1486857600

Sellers:

15 keys:

http://i.imgur.com/a2wgWlJ.jpg

http://backpack.tf/u/76561198070833573

Sales at:

10

12 (2x)

13

14

16

Most sales at 13 and lower sold in a short amount of time. Excluding those sales.

Going with 14-16.