Too many unsold at 4 keys and this item can easily be found for 3-3.5 keys. Proofs below:

Selling for 3 keys:

http://www.tf2outpost.com/trade/8743369

http://www.tf2outpost.com/trade/8682057

Selling for 3 keys 1.33 ref (3.36 keys):

http://www.tf2outpost.com/trade/8666947 (1 add)

http://www.tf2outpost.com/trade/8669140

Selling for 3 keys 1.66 ref (3.45 keys):

http://www.tf2outpost.com/trade/8682237 (3 days ago)

Selling for 3.5 keys:

http://www.tf2outpost.com/trade/8733600

Unsold for 3 keys 2 ref (3.55 keys):

http://www.tf2outpost.com/trade/8460363

http://www.tf2outpost.com/trade/8033140 (1 month ago)

Unsold for 3 keys 2.88 ref (3.79 keys):

http://www.tf2outpost.com/trade/8722991 (1 day ago)

Selling for 3 keys 3 ref (3.82 keys):

http://www.tf2outpost.com/trade/8711897

Unsold for 4 keys:

http://www.tf2outpost.com/trade/8641446 (5 days ago)

http://www.tf2outpost.com/trade/8718302 (2 days ago)

http://www.tf2outpost.com/trade/8747345 (22 hours ago)

http://www.tf2outpost.com/trade/8736505 (1 day)

http://www.tf2outpost.com/trade/8759979 (8 hours)

http://www.tf2outpost.com/trade/8732112 (1 day ago)

http://www.tf2outpost.com/trade/8449430 (2 weeks, lowered down to 3.82 keys but still no buyer)

http://www.tf2outpost.com/trade/8552962 (1 week)

http://www.tf2outpost.com/trade/8077121 (4 weeks)

http://www.tf2outpost.com/trade/8694464 (3 days)