Many unsuccessful sellers for 4 ref. But still some are. People sell for prices from 3.66 to 4 ref, therefore the range.

Selling for 3.66 ref

http://www.tf2outpost.com/trade/15295876 Unsold.

http://www.tf2outpost.com/trade/15295421 Unsold.

http://www.tf2outpost.com/trade/15290643 Unsold.

http://www.tf2outpost.com/trade/15282317 Unsold.

http://www.tf2outpost.com/trade/15280585 Unsold.

http://www.tf2outpost.com/trade/15174609 Unsold.

http://www.tf2outpost.com/trade/14941123 Unsold.

Selling for 3.77 ref

http://www.tf2outpost.com/trade/15247822 Unsold.

Selling for 3.88 ref

http://www.tf2outpost.com/trade/15268737 Unsold.

http://www.tf2outpost.com/trade/15152426 Unsold.

http://www.tf2outpost.com/trade/15249407 Added, not sold.

Selling for 4 ref (Proof it's still possible)

http://www.tf2outpost.com/trade/14903084 2 offers recently.

Selling for 3.66-4 ref

http://www.tf2outpost.com/trade/15286592 3.66-4 ref is the dirty version.

Unsolds for 4 ref

http://www.tf2outpost.com/trade/15231437 2 days.

http://www.tf2outpost.com/trade/15213786 3 days.

http://www.tf2outpost.com/trade/15201311 4 days.