As per requested, i'm bogged down now.

Every single sale i can trace for C9 Spartans. All to prove two sales are outliers.

Sale 1 OUTLIER

http://www.tf2outpost.com/trade/24718214 Sold for Blizz Bucket

B/O for Tartan was 2.2

X = 1.1*0.9

X = 1

Bucket http://backpack.tf/item/1522134411

Tartan http://backpack.tf/item/3369358222

Sale 2

http://www.tf2outpost.com/trade/24899701 Sold for Pro KS Aussie Stickybomb Launcher

Tartan had no trade, presuming offered

X = 2.4

Sticky http://backpack.tf/item/2165659200

Tartan http://backpack.tf/item/2794751522

Mini for Sticky

http://steamcommunity.com/market/listings/440/Strange%20Professional%20Killstreak%20Australium%20Stickybomb%20Launcher Sold for $96.99 on Jan 7th, closest date

$96.99 = $83.40 in SCM (Using BP.TF's new SCM counter)

Keys were $2.36 on Feb 7th

$83.40/$2.36 = 35.3 keys = 2.4

Sale 3

http://www.tf2outpost.com/trade/24941036 Sold for DBD Shako

B/O for Tartan was 2

X = 2*0.9

X = 1.8

Shako http://backpack.tf/item/2345048569

Tartan http://backpack.tf/item/2154142749

Mini for Shako

http://www.tf2outpost.com/trade/24960570 B/O of 2, using 2

Sale 4 QUICKSELL

http://www.tf2outpost.com/trade/24849201 Sold for Aussie Amby

B/O for Tartan was 25 keys (1.9)

B/O for Amby was 18 keys (1.4)

X = 1.2*0.9

X = 1.1

Amby http://backpack.tf/item/2193275600

Tartan http://backpack.tf/item/2154142749

Sale 5

http://www.tf2outpost.com/trade/24442884 Sold for Skull Toe

B/O for Toe was 3.2

B/O for Spartan was 3.3

Tartan was most likely offered on Toe, he had offered previously on that trade.

X = 2.4

Toe http://backpack.tf/item/1194445781

Tartan http://backpack.tf/item/2154142749

Mini for Toe

http://www.tf2outpost.com/trade/24410148 Sold for Vivid Pickehaube

B/O for Toe was 2.5

B/O for Pick was 2.8

X = 2.7*0.9

X = 2.4

Pick http://backpack.tf/item/980544682

Toe http://backpack.tf/item/1194445781

Seller

http://www.tf2outpost.com/trade/25021766 Selling for 2