Counter to the 5.5 bud suggestion

Sale 1:

5 buds

http://puu.sh/dqm4w/5e456816ca.png

Sale 2:

No link available

Sold for orb fire thirst blood, orb fire slopers, max's, festive rl

http://puu.sh/dqm2p/210dd47b9e.png

Price: (1.65+1.26)*0.9+5 = 7.6

Outlier http://snag.gy/tHg2y.jpg

Sale 3:

Max's, 1 bud, 15 keys

Buyer before: http://backpack.tf/profiles/76561198091632624?time=1414652400

Buyer after: http://backpack.tf/profiles/76561198091632624?time=1414738800

3 buds in the buyer's backpack went to the same person(BLUE), who sold the max.

max's history http://backpack.tf/item/277368971

Price:3.3+1+1.04 = 5.04

Sale 4: http://www.tf2outpost.com/trade/23456776

Sold for GE fro, steaming bonk boy

Price: (3.43+2.25)*0.9 = 5

Sale 5:

http://www.tf2outpost.com/trade/23758842

Sold with Cauldron Sthlhelm for HOUWAR

Price: 0.9 * (10.51 - 0.9 * 4.8) = 5.5

Sale 6:

http://www.tf2outpost.com/trade/23397538

Sold for 4 buds 15 keys

buyer before:http://backpack.tf/profiles/76561198044062952?time=1416124800

buyer after : http://backpack.tf/profiles/76561198044062952?time=1416211200

Price: 5.04

Sale 7:

http://www.tf2outpost.com/trade/23607152

Sold for 5.4

Sale 8:

http://www.tf2outpost.com/trade/22990618

http://uploadir.com/u/0nwqe2ij

5.5 buds

There may have been a couple more sales, but this should be enough to prove that the price is stable.