If you can sell this for 4 ref you should consider yourself lucky.

There are currently six classifieds listings at 3.66 ref on backpack.tf, far more than is expected: http://i.imgur.com/CaHCSmo.png

Unsolds at 4:

http://www.tf2outpost.com/trade/25293198 - 7 months and still hasn't sold

http://www.tf2outpost.com/trade/27196794 - 10 days

http://www.tf2outpost.com/trade/27216649 - 6 days

http://www.tf2outpost.com/trade/27225232 - 5 days

http://www.tf2outpost.com/trade/27236688 - 3 days (specifically the Boston Boom-Bringer)

http://www.tf2outpost.com/trade/27238113 - 3 days

http://www.tf2outpost.com/trade/27239435 - 3 days

http://www.tf2outpost.com/trade/27254678 - 1 day

Yes, I own one; but this price suggestion would actually hurt any profit from this item.