Sale 1:

Sold for Terror-Watt Stainless Pot (Mini at 19 below)

http://www.tf2outpost.com/trade/28700014 - B/O of 19

Seller: http://backpack.tf/profiles/76561198089869485#!/compare/1483574400/1483660800

Buyer: http://backpack.tf/profiles/76561198209268289#!/compare/1483488000/1483660800

X = 19

Sale 2:

Sold for 16 keys

http://www.tf2outpost.com/trade/28664545 - B/O of 16

Seller: http://backpack.tf/profiles/76561198265184521#!/compare/1483142400/1483228800

Buyer: http://backpack.tf/profiles/76561197999059147#!/compare/1483142400/1483228800

X = 16

Sale 3:

Sold with 2 keys in items for Dead Presidents Thirst Blood (17)

No outpost

Seller: http://backpack.tf/profiles/76561198084253260#!/compare/1483488000/1483574400

Buyer: http://backpack.tf/profiles/76561198089869485#!/compare/1483488000/1483574400

X = 15

Sale 4:

Sold for 15 keys

No outpost

Seller: http://backpack.tf/profiles/76561198060448233#!/compare/1484697600/1484784000

Buyer: http://backpack.tf/profiles/76561198079606144#!/compare/1484611200/1484697600

X = 15

Sale 5:

Sold for 14 keys (Buyer’s backpack)

No outpost

Seller: http://backpack.tf/profiles/76561198120382814#!/compare/1481760000/1481846400

Buyer: http://backpack.tf/profiles/76561198265184521#!/compare/1481414400/1481846400

X = 14

Sale 6:

Quicksold for 14 keys

http://www.tf2outpost.com/trade/28738645 - Deleted B/O

Seller: http://backpack.tf/profiles/76561198002757046#!/compare/1485216000/1485302400

Buyer: http://backpack.tf/profiles/76561198197828049#!/compare/1485302400/1485388800

X = 14

Sale 7:

Quicksold for 13 keys

http://www.tf2outpost.com/trade/28743969 - B/O of 15

Seller: http://backpack.tf/profiles/76561198197828049#!/compare/1485388800/1485475200

Buyer: http://backpack.tf/profiles/76561198048851745#!/compare/1485475200/1485561600

X = 13

Sale 8:

Sold for 13 keys to Rubi

Seller: http://backpack.tf/profiles/76561198079606144#!/compare/1485216000/1486684800

Buyer: http://backpack.tf/profiles/76561198002757046#!/compare/1485129600/1485216000

X = 13

Sale 9:

Sold with Strange Spec. KS Scattergun and 6 ref (>1.5) for Orbiting Planets Drill Sergeant (14)

No outpost

Seller: http://backpack.tf/profiles/76561198209268289#!/compare/1483488000/1483660800

Buyer: http://backpack.tf/profiles/76561198124516652#!/compare/1483574400/1483660800

X = 12

Sale 10:

Sold for Pro. KS Australium FaN (12) + Strange Flying Guillotine (<0.5)

http://www.tf2outpost.com/trade/28714730 - B/O of 17

Seller: http://backpack.tf/profiles/76561198241303512#!/compare/1484265600/1484352000

Buyer: http://backpack.tf/profiles/76561198155826465#!/compare/1484179200/1484352000

X = 12

Terror-Watt Stainless Pot Mini:

http://backpack.tf/suggestion/58bfeece0e2cad74723673a6

Sellers:

15 keys:

http://i.imgur.com/PrzTMKb.png - 4 days, probably lowered before then.

http://backpack.tf/u/76561198048851745

18 keys:

http://i.imgur.com/7VSDEoR.png

http://backpack.tf/u/76561198064714626

http://www.tf2outpost.com/trade/28314612 - 8 months?

Sales at:

12 (2x)

13 (2x)

14 (2x)

15 (2x)

16

19

Various quicksells in the 12-14 range, and Rubi seems to be buying for 13. Excluding 14 and below.

Not taking into account the 18 key seller that may have been up for 8 months (gap in the time periods of the comments, doubt it was open the whole 8 months), 19 looks like an outlier. Excluding 19.

Going with 15-16.