Sale 1:

Sold for Stormy Storm Bombing Run (11.5), keys were not involved.

http://www.tf2outpost.com/trade/28644998 - No visible B/O

Seller: http://backpack.tf/profiles/76561198192602363#!/compare/1485043200/1485129600

Buyer: http://backpack.tf/profiles/76561198140287487#!/compare/1485043200/1485129600

X = 12

Sale 2:

Sold for 10 keys

http://www.tf2outpost.com/trade/28693908 - B/O of 10

Seller: http://backpack.tf/profiles/76561198136286178#!/compare/1483488000/1483574400

Buyer: http://backpack.tf/profiles/76561198257902792#!/compare/1483315200/1483488000

X = 10

Sale 3:

Sold for 10 keys

http://www.tf2outpost.com/trade/28761565 - B/O of 10

Seller: http://backpack.tf/profiles/76561198053172418#!/compare/1486339200/1486512000

Buyer: http://backpack.tf/profiles/76561198069666384#!/compare/1486252800/1486425600

X = 10

Sale 4:

Sold for 10 keys?

http://www.tf2outpost.com/trade/28769355 - B/O of 12

Seller: http://backpack.tf/profiles/76561198069666384#!/compare/1486512000/1486598400

Buyer: http://backpack.tf/profiles/76561198126834284#!/compare/1486512000/1486598400

X = 10

Sale 5:

Quicksold for 9 keys + <0.5 keys in items

No outpost

Seller: http://backpack.tf/profiles/76561198138563445#!/compare/1481068800/1481155200

Buyer: http://backpack.tf/profiles/76561198071491128#!/compare/1481068800/1482019200

X = 9

Sale 6:

Quicksold for 9 keys

http://www.tf2outpost.com/trade/28649266 - B/O of 12.5, re-listed to http://www.tf2outpost.com/trade/28669333 - B/O of 13, re-listed to http://www.tf2outpost.com/trade/28673070 - B/O of 13, re-listed to http://www.tf2outpost.com/trade/28754056 - B/O of 9 (1 day at 9)

Seller: http://backpack.tf/profiles/76561198071491128#!/compare/1484697600/1485907200

Buyer: http://backpack.tf/profiles/76561198053008714#!/compare/1485734400/1485907200

X = 9

Sale 7:

Quicksold for 9 keys

http://www.tf2outpost.com/trade/28689377 - B/O of 10

Seller: http://backpack.tf/profiles/76561198153043737#!/compare/1483142400/1483228800

Buyer: http://backpack.tf/profiles/76561198106495563#!/compare/1482969600/1483228800

X = 9

Sale 9:

Sold with ~5.5 keys in items for Stormy Storm Bombing Run (11.5)

No outpost

Seller: http://backpack.tf/profiles/76561198211757389#!/compare/1484524800/1486512000

Buyer: http://backpack.tf/profiles/76561198072099588#!/compare/1484611200/1484697600

X = 6

Sale 10:

Sold with ~5.5 keys in items for Stormy Storm Bombing Run (11.5)…again. Same items, different buyer. I’m very confused.

http://www.tf2outpost.com/trade/28726887 - B/O of 10

Seller: http://backpack.tf/profiles/76561198072099588#!/compare/1484697600/1484956800

Buyer: http://backpack.tf/profiles/76561198115047547#!/compare/1484870400/1484956800

X = 6

Sale 11:

Sold with junk for Smoking Helmet Without a Home

Seller: http://backpack.tf/profiles/76561198115047547#!/compare/1485475200/1485648000

Buyer: http://backpack.tf/profiles/76561198002186909#!/compare/1485561600/1485648000

Should be used to update the Helmet

Sale 12:

Sold with 2 keys + Fabricator (<0.5) for Orbiting Planets Rebel Rouser

Seller: http://backpack.tf/profiles/76561198261444833#!/compare/1483056000/1483142400

Buyer: http://backpack.tf/profiles/76561198153043737#!/compare/1483056000/1483142400

Should be used to update the Rouser

Sellers:

10 keys:

http://i.imgur.com/15f2Qac.png - 12 days

http://backpack.tf/u/76561198002757046

http://www.tf2outpost.com/trade/28776073

11 keys:

http://i.imgur.com/WFY1VDG.png - 8 days

http://backpack.tf/u/76561198190577279

http://www.tf2outpost.com/trade/28763172

http://i.imgur.com/yJW6REa.png

http://backpack.tf/u/76561198195483499

http://www.tf2outpost.com/trade/28771400 - 3 days

Offers:

http://www.tf2outpost.com/trade/28654650 - 2 months

http://backpack.tf/u/76561198026577539

Sales at:

6 (2x)

9 (3x)

10 (3x)

12

6 is obviously way too low. Excluding 6.

Sales at 9 quicksold. Excluding 9.

Going with 10-12.