Hmm

Sale 1:

Sold for 2 painted Bill’s (4.3) + ~7.5 keys in items

No outpost

Seller: http://backpack.tf/profiles/76561198131066806#!/compare/1461110400/1461196800

Buyer?: http://backpack.tf/profiles/76561197990998139#!/compare/1459036800/1461283200

X = 13

Sale 2:

Sold for 12 keys in (decent) items

No outpost

Seller: http://backpack.tf/profiles/76561198113595239#!/compare/1456992000/1457337600

Buyer: http://backpack.tf/profiles/76561198097651432#!/compare/1456819200/1457337600

X = 12

Sale 3:

Sold for 11 keys

http://www.tf2outpost.com/trade/28108010 - B/O of 11

Seller: http://backpack.tf/profiles/76561198167042165#!/compare/1462320000/1462752000

Buyer: http://backpack.tf/profiles/76561198071605951#!/compare/1462579200/1463097600

X = 11

Sale 4:

Sold for 3 keys + 46.55 ref (2.4) + ~5 keys in items

http://www.tf2outpost.com/trade/28106309 - B/O of 10

Seller: http://backpack.tf/profiles/76561198129088942#!/compare/1461369600/1461456000

Buyer: http://backpack.tf/profiles/76561198167042165#!/compare/1461369600/1461456000

X = 10 (Capped by B/O)

Sale 5:

Sold for 4 keys + 2 keys in ref + 2 keys in items

http://www.tf2outpost.com/trade/27887171 - B/O of 10

Seller: http://backpack.tf/profiles/76561198112971699#!/compare/1456819200/1456992000

Buyer: http://backpack.tf/profiles/76561198113595239#!/compare/1456905600/1456992000

X = 8

No current sellers

Sales at:

8

10

11

12

13

8 is low, due to the buyer: http://puu.sh/pacrs/5812250e77.png

Going with 10-13