I own one, yes, but it's pro ks and not for sale.

Top Classifieds:

http://gyazo.com/f09e7d77da08f9b6c22af20f28fc0268

1x 2 ref

2x 2.33

2x 2.66

1x 3 ref

1x 4 ref

2x 6 ref

1x 6.11

Sellers:

There are lots of trades for this item saying "backpack.tf price" or "2 ref" but nearly all have sold.

2 ref:

http://www.tf2outpost.com/trade/25328386

2.22:

http://www.tf2outpost.com/trade/25351247

2.66:

http://www.tf2outpost.com/trade/25349076

Sales/Solds:

2 ref:

http://www.tf2outpost.com/trade/25192137

http://www.tf2outpost.com/trade/25275422

http://www.tf2outpost.com/trade/25350821

http://www.tf2outpost.com/trade/25175845

http://www.tf2outpost.com/trade/25311571

2.33:

http://www.tf2outpost.com/trade/25180519

3 ref:

http://www.tf2outpost.com/trade/25256235

http://i.imgur.com/0NN8T52.png [Courtesy of Lady Drug]

3.33:

http://i.imgur.com/5lFqnly.png [Courtesy of Lady Drug]

4 ref:

http://www.tf2outpost.com/trade/25262784

Buyers:

2 ref:

http://www.tf2outpost.com/trade/25183330

http://www.tf2outpost.com/trade/25356164

http://www.tf2outpost.com/trade/25355852

http://www.tf2outpost.com/trade/25345211

http://www.tf2outpost.com/trade/25327750

2.11:

http://www.tf2outpost.com/trade/25207689

2.22:

http://www.tf2outpost.com/trade/25274494 [Unbumped, invalid]

As always, please try and keep the comments relevant, please don't make comment comprised only of "upvote" or "downvote". Counter-proof / supportive proof is always appreciated!