Team Fortress 2
Counter-Strike: Global Offensive
15 month old price!
Sold for Australium Knife (20*0.95) + Orbiting Fire Mullet (13*0.9) = 19 + 11.7 = 30.7 (rounding to 31 keys)
http://backpack.tf/profiles/76561198047433991?time=1434956400 (June 22nd)
http://backpack.tf/profiles/76561198047433991?time=1435042800 (June 23rd)
Sale 2: (outlier)
Sold with Terror-Watt Frenchman's Beret for Stormy Storm Charmer's Chapeau
X + 13 = 28*0.9
X = 12.2 (rounding to 12 keys)
http://backpack.tf/profiles/76561198064776045?time=1431932400 (May 18th)
http://backpack.tf/profiles/76561198064776045?time=1432018800 (May 19th)
Sold for 22 keys + Sweets (~4*0.9) = 22 + 3.6 = 25.6 (rounding to 26 keys)
http://backpack.tf/profiles/76561198164344801?time=1431327600 (May 11th)
http://backpack.tf/profiles/76561198164344801?time=1431414000 (May 12th)
Sold for Max's Severed Head = ~26 keys (at the time of sale)
[no outpost trade]
http://backpack.tf/profiles/76561197974841166?time=1431154800 (May 9th)
http://backpack.tf/profiles/76561197974841166?time=1431241200 (May 10th)
Mini-suggestion for Stormy Storm Charmer's Chapeau*:
http://www.tf2outpost.com/trade/26252702 - B/O of 28 keys (~1 week)
Because of the following given B/Os and no offers over 31 keys, going to call Sale 1 an outlier.
http://www.tf2outpost.com/trade/26215048 - B/O of 27 keys
http://www.tf2outpost.com/trade/25992157 - B/O of 29 keys
http://i.imgur.com/6UNCmx6.png - B/Os of 28 and 30 keys
Two valid sales at 26 keys. Taking a final flat value of 26 keys.
Feel free to support/counter my suggestion!