Market flooded with cheaper keys -> People don't try at higher end -> 1.5 doesn't sell.

http://backpack.tf/classifieds/search/id/52702d014cd7b8f7728b456b

1.1 / 1.2 / several 1.3 / lots of unsolds @ 1.5

http://www.tf2outpost.com/trade/15415491 - Sold for 6 ref

http://www.tf2outpost.com/trade/15414385 - Selling for an Acorns Key

http://puu.sh/56eD4.png - Bought for 1.1

http://www.tf2outpost.com/trade/15411387 - Sold for 1.2

http://www.tf2outpost.com/trade/15412067 - Sold for 1.2

http://www.tf2outpost.com/trade/15411825 - Sold for 1.2

http://www.tf2outpost.com/trade/15418447 - Sold for 1.2

http://www.tf2outpost.com/trade/15414771 - Sold for 1.2

http://www.tf2outpost.com/trade/15421305 - Sold for 1.2

http://www.tf2outpost.com/trade/15412285 - Sold for 1.2

http://www.tf2outpost.com/trade/15422643 - Sold for 1.2

http://www.tf2outpost.com/trade/15422626 - Selling for 1.2

http://www.tf2outpost.com/trade/15422479 - Selling for 1.2

http://www.tf2outpost.com/trade/15410540 - Sold for 1.2

http://bazaar.tf/trade/513377 - Sold for 1.2

http://www.tf2outpost.com/trade/15415075 - Sold for 1.2

http://www.tf2outpost.com/trade/15415559 - Sold for 1.2

http://www.tf2outpost.com/trade/15412684 - Sold for 1.2

http://www.tf2outpost.com/trade/15413881 - Sold for 1.2

http://www.tf2outpost.com/trade/15410502 - Sold for 1.3

http://www.tf2outpost.com/trade/15422874 - Sold for 1.3

http://www.tf2outpost.com/trade/15412940 - Sold for 1.3

http://www.tf2outpost.com/trade/15416370 - Sold for 1.3

http://www.tf2outpost.com/trade/15419522 - Selling for 1.3

http://www.tf2outpost.com/trade/15421389 - Selling for 1.3

http://www.tf2outpost.com/trade/15423016 - Selling for 1.3

http://www.tf2outpost.com/trade/15410303 - Sold for 1.3

http://www.tf2outpost.com/trade/15410328 - Selling for 1.3

Unsolds at 1.5:

http://www.tf2outpost.com/trade/15414407

http://bazaar.tf/trade/513282

http://www.tf2outpost.com/trade/15410401

http://www.tf2outpost.com/trade/15420689

http://www.tf2outpost.com/trade/15397240

http://www.tf2outpost.com/trade/15353932

http://www.tf2outpost.com/trade/15357499

http://www.tf2outpost.com/trade/15381648

http://www.tf2outpost.com/trade/15402508

All proof is fresh, from today.

http://steamcommunity.com/market/listings/440/Spooky%20Key

Averages out at $2.70, ~1.1 keys.

1.1 - Possible to get

1.2 - Most common.

1.3 - Sellable, not as quick, tho.

1.4/1.5 - Not sellable.

No sign of incluiding 1 key flat in the range yet.