Jesus christ.

You want fluctuation? THIS is fluctuation.

Sold for 12 Keys

http://backpack.tf/profiles/76561198081795383#!/compare/1464048000/1464220800

Sold for an Aces High Whirly Warrior(Outdated at 17 Keys)

http://backpack.tf/profiles/76561198080524846#!/compare/1464825600/146491200

Added 3 Keys for an Orbiting Planets Rimmed Raincatcher(Outdated at 13 Keys)(10 Keys total)

http://backpack.tf/profiles/76561198156574365#!/compare/1464825600/1464912000

http://backpack.tf/profiles/76561198080524846#!/compare/1464912000/1465084800

Sold for an Australium Pro KS SMG(~10 Keys)

http://backpack.tf/profiles/76561198116979356#!/compare/1462492800/1462665600

Added 1 Key for a Dead Presidents Madame Dixie(Outtdated at 18 Keys)(17 Keys total)

http://backpack.tf/profiles/76561198125399339#!/compare/1458864000/1458950400

http://www.tf2outpost.com/trade/27986447 B/O of 18

Sold for a Magnetic Hat Protector Head Full of Hot Air(22 Keys)(B/O was 21)

http://backpack.tf/profiles/76561198125869453#!/compare/1459296000/1459382400

http://www.tf2outpost.com/trade/28010988

Added a Burstchester(3.5 Keys at the time) for an Orbiting Fire Virtual Reality Headset(15.5 Keys)(12 Keys total)

http://backpack.tf/profiles/76561198125869453#!/compare/1458950400/1459036800

http://backpack.tf/profiles/76561198201557765#!/compare/1458950400/1459036800

Sold for a Steaming Towering Pillar of Hats(Outdated at 15 Keys) and ~1.5 Keys in Sweets(16.5 Keys total)

http://backpack.tf/profiles/76561198155957933#!/compare/1459641600/1459814400

Sold for a Smoking Le Party Phantom(Outdated at 23 Keys) and ~1 Key in Sweets(24 Keys total)

http://backpack.tf/profiles/76561198192740165#!/compare/1459468800/1459555200

Sold for a Batsaber(12 Keys at the time)

http://backpack.tf/profiles/76561198190594053#!/compare/1459382400/1459641600

http://www.tf2outpost.com/trade/28036566 B/O was 15

Sold for 14 Keys

http://backpack.tf/profiles/76561198021383012#!/compare/1461715200/1461801600

Sold for 12 Keys

http://backpack.tf/profiles/76561198141878168#!/compare/1458198000/1459036800

Sold for an Overclocked Ol' Snaggletooth(12 Keys)

http://backpack.tf/profiles/76561198076020691#!/compare/1463702400/1463788800

Sold for a Terror-Watt Birdcage(Outdated at 19 Keys) and ~2 Keys in Sweets(21 Keys total)

http://backpack.tf/profiles/76561198143118102#!/compare/1464480000/1464566400

Sold for a Nuts & Bolts Handyman's Handle(Outdated at 9.5 Keys) ad a #87 Made Man(~1.5 Keys?)(~11 Keys total)

http://backpack.tf/profiles/76561198147995236#!/compare/1465084800/1465171200

PRO KS SALES

Sold for an Orbiting Fire Frenchman's Beret(Outdated at 13 Keys) and ~4 Keys in Sweets(17 Keys total)

http://backpack.tf/profiles/76561198152141326#!/compare/1459555200/1460073600

Sold for a Grnuine Robo-Sandvich(18 Keys at the time)

http://backpack.tf/profiles/76561198039575316#!/compare/1460246400/1460505600

http://www.tf2outpost.com/trade/28068644 B/O was 20

Sold for a Strange Festive Pro KS Crusader's Crossbow(~11 Keys)

http://backpack.tf/profiles/76561198114871296#!/compare/1458864000/1459036800

Quicksold for 18 Keys(1 Key was in metal)

http://backpack.tf/profiles/76561198083285253#!/compare/1463961600/1464048000

http://www.tf2outpost.com/trade/28194247

Added 5 Keys for a Max's Severed Head(29.5 Keys, rounding to 30)(25 Keys total)

http://backpack.tf/profiles/76561198146482769#!/compare/1461283200/1461369600

Sold for a Strange Festive Huntsman(~6 Keys) and a Strange Deep Cover Operator(~4 Keys)(10 Keys total)

http://backpack.tf/profiles/76561198081002938#!/compare/1463011200/1463097600

Added 3 Keys for an Australium Black Box(18 Keys)(15 Keys total)

http://backpack.tf/profiles/76561198127551959#!/compare/1463961600/1464048000

http://backpack.tf/profiles/76561198019556015#!/compare/1463961600/1464048000

Sellers:

http://www.tf2outpost.com/trade/28237250 20 Keys, young

http://www.tf2outpost.com/trade/28237180 9 Keys, quicksold i guess

http://www.tf2outpost.com/trade/28221798 15 Keys, 5 days unsold

So we have Non-Pro KS sales at:

~10, 10, ~11, 12, 12, 12, 12, 12, 14, ~16.5, ~17, ~17, 21 and ~24, with B/Os of 15 and 18.

And we have Pro KS sales at:

10, 15, ~17, 18(qs), 18 and 25, with a B/O of 20.

Given that all of the ~17 key sales come from outdated unusual prices(and frankly, those sales are better used for those respective unus), and most sellers asking for ~15-20, going to go with 12-14 keys here.

12 is an extremely common point, and 14 represents the loads of sales at higher, without going above 15 Key B/Os.

tl;dr: 12-14 Keys should be fine.

Additional Proof/Counter-Proof/Constructive Criticism/Feedback is always appreciated.