Peasant was right, this needed a range (after thinking for awhile, I had to agree with you):

Although there were 2 trades pricing this at 1 key, but many remained unsold and only 1 sales last week. 2.33 as a flat seems legit at the moment.

Unsold for 1 key:

http://www.tf2outpost.com/trade/7029385 (2 months)

http://www.tf2outpost.com/trade/7964649 (1 month)

Sold for 1 key:

http://www.tf2outpost.com/trade/8215219

Being offered 2.33 ref:

http://www.tf2outpost.com/trade/6552856 (buyer assumed that it has 25 uses, but this one only has 20)

Pricing each at 2.33 ref:

http://www.tf2outpost.com/trade/8713369 (selling as a set)