http://www.tf2outpost.com/trade/14078112 - 5 ref (1 month)

http://www.tf2outpost.com/trade/16008653 - 5.66 (7 hours)

http://www.tf2outpost.com/trade/15750754 - 5.88 (1 week)

http://www.tf2outpost.com/trade/15545556 - 1 key (3 weeks)

http://www.tf2outpost.com/trade/15171198 - 1 key (1 month)

These are the only trades I found on OP that have a price, most of which are unsold for extended periods of time. Keeping this conservative, and rounding the 5.88 off to get a neat range ^.^ Vote accordingly.

Help / Constructive Criticism / Additional Proof / Counter-Proof is ALWAYS welcome! >;3