http://www.tf2outpost.com/trade/4808891 (bought for 1 ref)

http://www.tf2outpost.com/trade/4793163 (offered for 1 ref)

http://www.tf2outpost.com/trade/4923640 (sold for 0.66 ref)

Not a lot evidence on outpost, but I couldn't find any 1.33 offers.

Oh my bad the 3rd link was an offer of 0.66 but another trader bought it. Apologies.

These are somewhat rare. The one's asking for 1 refined or lower have all sold and the lowest priced ones available are 1.33 refined. I think this price range is reasonable.