This is a resuggestion of: http://backpack.tf/vote/id/52a0dafe4cd7b841588b456c Apparently the original suggestor doesn't want to include the "qs" to the proof so I might as well do this. Here be proof:

The 1st sale which was stated as a "quick sale" (Which actually took 2 months) was sold for 6 pure: http://www.tf2outpost.com/trade/14726131

2nd sale is made by the original suggester who paid Sunbeams Soldier's Slope Scopers for it. Using the original price and unusual overpay we get 7,9 buds. Trade seen here: http://www.tf2outpost.com/trade/16111350

So the range would be 6 - 7,9.