http://backpack.tf/classifieds/search/id/52b49db94dd7b892778b4567 (2 for 1 key, lots for 1.2, lots for 1.3, lots for 1.4, 3 fro 1.5, lots for 1.6)

Proof:

Unsold:

1.6 keys:

http://www.tf2outpost.com/trade/16816247 (1 day)

http://www.tf2outpost.com/trade/16857361 (<1 day)

http://www.tf2outpost.com/trade/16835896 (<1 day)

http://www.tf2outpost.com/trade/16848296 (<1 day)

http://www.tf2outpost.com/trade/16828531 (<1 day)

http://www.tf2outpost.com/trade/16845339 (<1 day)

http://www.tf2outpost.com/trade/16738735 (3 days)

http://www.tf2outpost.com/trade/16858982 (<1 day)

http://www.tf2outpost.com/trade/16802408 (1 day)

Selling:

1.5 keys:

http://www.tf2outpost.com/trade/16828185 (<1 day)

http://www.tf2outpost.com/trade/16854121 (<1 day)

http://www.tf2outpost.com/trade/16857339 (<1 day)

http://www.tf2outpost.com/trade/16808498 (<1 day)

http://www.tf2outpost.com/trade/16856217 (<1 day)

1.44 keys:

http://www.tf2outpost.com/trade/16827219 (<1 day)

http://www.tf2outpost.com/trade/16849174 (<1 day)

http://www.tf2outpost.com/trade/16849604 (<1 day)

1.4 keys:

http://www.tf2outpost.com/trade/16833997 (<1 day)

1.3 keys:

http://www.tf2outpost.com/trade/16856650 (<1 day)

http://www.tf2outpost.com/trade/16853533 (<1 day)

http://www.tf2outpost.com/trade/16830689 (<1 day)

http://www.tf2outpost.com/trade/16858819 (<1 day)

http://www.tf2outpost.com/trade/16855200 (<1 day)

1.1 keys:

http://www.tf2outpost.com/trade/16851411 (<1 day)

Newish item so trades are fairly young. 1.6 isn't selling. Many available at 1.3-1.5.

Thanks for voting : )