3 month old price!

Sale 1:

Sold for 45 keys

http://www.tf2outpost.com/trade/27136794

http://backpack.tf/profiles/76561198031371895?time=1443423600 (September 28th)

http://backpack.tf/profiles/76561198031371895?time=1443510000 (September 29th)

http://backpack.tf/profiles/76561198031371895?time=1443423600&compare=1443510000

http://i.imgur.com/BtzeSUU.png

Sale 2:

Sold with Sweets (~6*0.9) for Scorching Flames Berliner's Bucket Helm (53*0.9) = 42.3 (rounding to 42 keys)

http://www.tf2outpost.com/trade/26931282

http://backpack.tf/profiles/76561198057452720?time=1441004400 (August 31st)

http://backpack.tf/profiles/76561198057452720?time=1441609200 (September 7th)

http://backpack.tf/profiles/76561198057452720?time=1441004400&compare=1441609200

Sale 3:

Sold for 38 keys + Sweets (~0.92*0.9) = ~38.82 (rounding to 39 keys)

http://www.tf2outpost.com/trade/26978006

http://backpack.tf/profiles/76561198057452720?time=1441782000 (September 9th)

http://backpack.tf/profiles/76561198057452720?time=1441868400 (September 10th)

http://backpack.tf/profiles/76561198057452720?time=1441782000&compare=1441868400

Notes:

http://www.tf2outpost.com/trade/26931282 - B/O of 45 keys

http://www.tf2outpost.com/trade/26978006 - B/O of 45 keys

http://www.tf2outpost.com/trade/27136794 - B/O of 45 keys

Conclusion:

Three valid sales at 39, 42 and 45 keys. Taking a final range of 39-45 keys.

Feel free to support/counter my suggestion!