It looks like this part needs another bullet to the head!

Crate #82 keeps dropping them, people keep offloading them.

6.00

http://www.tf2outpost.com/trade/22232032 - (sold in 4 days)

http://www.tf2outpost.com/trade/22229150 - (sold in 2 days)

http://www.tf2outpost.com/trade/22227037 - (2 day unsold)

http://www.tf2outpost.com/trade/22205129 - (sold after 3 days)

http://www.tf2outpost.com/trade/22275211 - 5 days unsold

http://www.tf2outpost.com/trade/22386494 - unsold

http://www.tf2outpost.com/trade/22305888 - 4 days unsold - items*0.9

http://www.tf2outpost.com/trade/22046847 - items*0.9

http://www.tf2outpost.com/trade/22113713 - 6 days unsold

6.11

http://www.tf2outpost.com/trade/22155607 *2 - (sold in 3+ days)

6.22

http://www.tf2outpost.com/trade/22257619 - (6 days unsold)

6.33

http://www.tf2outpost.com/trade/21214583

http://www.tf2outpost.com/trade/22230300

http://www.tf2outpost.com/trade/22233160

http://www.tf2outpost.com/trade/22236768

http://www.tf2outpost.com/trade/22195990

http://www.tf2outpost.com/trade/22229931

http://www.tf2outpost.com/trade/22223514

http://www.tf2outpost.com/trade/21937225

http://www.tf2outpost.com/trade/22254040

http://www.tf2outpost.com/trade/22243467

http://www.tf2outpost.com/trade/22270991 - (6 days unsold, regular bumped)

http://www.tf2outpost.com/trade/22195990 - (1 week unsold)

http://www.tf2outpost.com/trade/22400406

http://www.tf2outpost.com/trade/22287026

http://www.tf2outpost.com/trade/22302475

http://www.tf2outpost.com/trade/22416022

There are many sellers at 'bp.tf price' or 1 key or 6.66, but they are just for the lazy buyer.

Side proof:

1) Classifieds on random days showing available items in this range.

http://imgur.com/YbsyUzi,laosgF9,BngMcY2#1

http://imgur.com/YbsyUzi,laosgF9,BngMcY2#2

2) Some outliers:

http://imgur.com/YbsyUzi,laosgF9,BngMcY2#0 - 4 bought at 5.33 ref since the last price update (and 1 @ 6)