3 of these exist, only two recent sales, however only one usable sale due to the other being a quicksale.

Sale #1 : 13 keys,

http://www.tf2outpost.com/trade/26949704 - Sold for pure.

http://backpack.tf/profiles/76561197995561518?time=1442818800 (21st of September)

http://backpack.tf/profiles/76561197995561518?time=1442905200 (22nd of September)

Comparison: http://backpack.tf/profiles/76561197995561518?time=1442818800&compare=1442905200

Seller's history above is a bit messy, buyer's history below shows keys going out, doesn't show the unusual coming in however item history does confirm the sale:

http://backpack.tf/item/2445469881 along with the individual key histories.

http://backpack.tf/profiles/76561198139749295?time=1442818800 (21st of September)

http://backpack.tf/profiles/76561198139749295?time=1442905200 (22nd of September)

Comparison: http://backpack.tf/profiles/76561198139749295?time=1442818800&compare=1442905200

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Buyer then went onto quicksale for 7-9 keys, actual trade value is not trackable due to incomplete histories.

Seller on outpost with b/o of 14 keys : http://www.tf2outpost.com/trade/27378168

Thats everything, suggesting at 13 keys flat, will resuggest if seller manages to sell, and as always feedback is appreciated.