Re-suggested with a better range.

Lowest seller I could find was ~1.1 keys.

Offers as high as ~1.7 keys with an add at 2 keys, but it doesn't sell fast enough at that price.

Offers

http://www.tf2outpost.com/trade/11223441 6 ref

http://www.tf2outpost.com/trade/11202806 6 ref, 1 key+1.33 ref, 1 key+1.66 ref

http://www.tf2outpost.com/trade/11116422 6 ref, 1 key+2.55 ref

Sold

http://www.tf2outpost.com/trade/11122997 5.88 ref (~1.1 keys)

http://www.tf2outpost.com/trade/11389527 6 ref (~1.1 keys)

http://www.tf2outpost.com/trade/10439726 6.33 ref (~1.2 keys)

http://www.tf2outpost.com/trade/11016152 1 key+1.44 ref (~1.3 keys), many adds

http://www.tf2outpost.com/trade/11355725 1 key+3 ref (~1.6 keys)

Selling for 1 key+3 ref

http://www.tf2outpost.com/trade/9693922 Added

Selling for 1 key+4 ref

http://www.tf2outpost.com/trade/9619943 offered 1 key+2.22 ref+geisha boy(~1 key+3.55 ref), offered 5 craft hats (min. 6.66 ref)

http://www.tf2outpost.com/trade/11383829 offered 1 key+1 ref

Selling for 2 keys

http://www.tf2outpost.com/trade/3120046 (not sure about possible price changes) added 1 week ago

http://www.tf2outpost.com/trade/9405996 8 ref offer, added for 2 keys

http://www.tf2outpost.com/trade/10176058 8 ref offer accepted

http://www.tf2outpost.com/trade/11046946 1 week

http://www.tf2outpost.com/trade/11223441 6 days