Counter suggesting. When it came to pure I checked the histories to ensure accuracy. All clean sales.

Sale 1:

Roboactive gentleman's ushanks(6.1) + orbiting fire front runner (1.5) + 19 keys

Occured 2 months ago, buds were 15.75 at that time: http://backpack.tf/vote/id/5450c5aeb88d8858018b4d6c

backpack before: http://backpack.tf/profiles/76561198042684142?time=1414479600

backpack after: http://backpack.tf/profiles/76561198042684142?time=1414566000

(6.1 + 1.5)0.9 + 19/15.75 =

8.04 rounded down to

8 buds

Sale 2:

backpack before: http://backpack.tf/profiles/76561198090077934?time=1419235200

backpack after: http://backpack.tf/profiles/76561198090077934?time=1419321600

Bought for 8 buds pure

Sale 3:

http://www.tf2outpost.com/trade/23889356

burning flames ol geezer (3.1) + 70 keys

Trade occured on the 2nd of December buds were 13.25 keys at that time:

http://backpack.tf/vote/id/5482967ab88d8823398b4742

backpack before: http://backpack.tf/profiles/76561198131175897?time=1417420800

backpack after: http://backpack.tf/profiles/76561198131175897?time=1417507200

(3.1)0.9 + 70/13.25 = 5.3 +2.8 =

8.1 buds

Outlier:

http://www.tf2outpost.com/trade/24164055 - sold for 85 keys (~5.9 buds)

Mini on front runner:

backpack before: http://backpack.tf/profiles/76561198042684142?time=1415865600

backpack after: http://backpack.tf/profiles/76561198042684142?time=1415952000

Sold for 23 keys

Occured 2 months ago, buds were 15.75 at that time: http://backpack.tf/vote/id/5450c5aeb88d8858018b4d6c

thus taking front runner at 1.46 rounded up to

1.5 buds