Sale #1:

Sold with ~1.5 keys in items for Gfetti Tricorne (13) + Steaming Bombing Run (11)

http://backpack.tf/profiles/76561198133041085?time=1444287600 (October 8th)

http://backpack.tf/profiles/76561198133041085?time=1444546800 (October 11th)

http://backpack.tf/profiles/76561198031385226?time=1444460400 (October 10th)

http://backpack.tf/profiles/76561198031385226?time=1444546800 (October 11th)

((13 + 11) * 0.9) - 1.5 = 20.1 keys; rounded to 20 keys

Sale #2:

http://www.tf2outpost.com/trade/27335104 Sold for 20 keys

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

Sale #3:

Sold with ~32 keys in Aussies + 8 keys for Scorching Glove (not usable)

http://backpack.tf/profiles/76561198148354688?time=1443596400 (September 30th)

http://backpack.tf/profiles/76561198148354688?time=1443682800 (October 1st)

Gfetti Tricorne:

http://www.tf2outpost.com/trade/27226465 Seller at 13 keys for 3 weeks

Steaming Bombing Run

Bombing Run from my experience should roughly be around ~11 keys

http://www.tf2outpost.com/trade/27263098 Seller at 12 for 2 weeks

It's around there. <3