Not difficult to find for less than 4.33 ref, but not impossible to sell for 4.33 ref.

Classifieds at time of suggestion:

http://i.imgur.com/X9tS6QI.png

1 x 3.33 ref

1 x 3.66 ref

3 x 4 ref

1 x 4.11 ref

5 x 4.22 ref

28 x 4.33 ref

1 x 4.55 ref

2 x 4.66 ref

1 x 5 ref

Sellers:

3.66 ref

http://www.tf2outpost.com/trade/22939480 - 3 days

4 ref

http://www.tf2outpost.com/trade/22983614 - 8 hours

http://www.tf2outpost.com/trade/22981740 - 10 hours

http://www.tf2outpost.com/trade/22966844 - 1 day

http://www.tf2outpost.com/trade/22951549 - 2 days (never bumped)

http://www.tf2outpost.com/trade/22941474 - 2 days (poorly bumped)

4.11 ref

http://www.tf2outpost.com/trade/22971598 - 1 day

4.22 ref

http://www.tf2outpost.com/trade/22988046 - 4 hours

http://www.tf2outpost.com/trade/22983025 - 8 hours

4.33 ref

http://www.tf2outpost.com/trade/22925631 - 4 days

http://www.tf2outpost.com/trade/22895297 - 5 days

http://www.tf2outpost.com/trade/22895297 - 5 days

http://www.tf2outpost.com/trade/22779706 - 1 week

http://www.tf2outpost.com/trade/22793865 - 1 week

Solds:

3.33 ref

http://www.tf2outpost.com/trade/22981712

3.88 ref

http://www.tf2outpost.com/trade/22952339

4 ref

http://www.tf2outpost.com/trade/22930892

http://www.tf2outpost.com/trade/22937378

http://www.tf2outpost.com/trade/22974615

http://www.tf2outpost.com/trade/22978373

4.11 ref

http://www.tf2outpost.com/trade/22930079

http://www.tf2outpost.com/trade/22943252

4.33 ref

http://www.tf2outpost.com/trade/22878235

http://www.tf2outpost.com/trade/22932059

http://www.tf2outpost.com/trade/22947881

http://www.tf2outpost.com/trade/22955897

http://www.tf2outpost.com/trade/22961385

http://www.tf2outpost.com/trade/22964151

Thanks to d0 (and Choccie ^^) for helping me. :3