Proof:

Sellers:

http://www.tf2outpost.com/trade/11535506 - Got an offer of 2.44 in no time

http://www.tf2outpost.com/trade/10913204 - Sold for 2.66

http://www.tf2outpost.com/trade/9805354 - Sold out at 2.66, some are recent

http://www.tf2outpost.com/trade/11480136 - Has offers of 2.33, 2.66, 3 and 4

http://www.tf2outpost.com/trade/11037135 - Has some adds at 5

http://www.tf2outpost.com/trade/9934671 - He sold few for 1 key

http://www.tf2outpost.com/trade/10918360 - Has some adds at 1 key

Buyers:

http://www.tf2outpost.com/trade/11584389 - Buying for 2.33

http://www.tf2outpost.com/trade/11540070 - Buying for 2.33, I don't see any adds, 1 day old

http://www.tf2outpost.com/trade/11418547 - Buying for 2.33, I don't see any adds, 6 days old

http://www.tf2outpost.com/trade/11410099 - Buying for 2.33, I don't see any adds, 6 days old

http://www.tf2outpost.com/trade/11277669 - Buying for 2.33, I don't see any adds, 1 week old

http://www.tf2outpost.com/trade/11490673 - Buying as many as possible for 2.33

http://www.tf2outpost.com/trade/9011305 - Buying as many as possible for 2.33

http://www.tf2outpost.com/trade/11446129 - Buying as many as possible for 2.33

http://www.tf2outpost.com/trade/11553753 - Buying as many as possible for 2.66

My buyers proof is thank to this suggestion: http://backpack.tf/vote/id/51b47fa0ba25362f4f000001

Since there's no proof of 3 (yet) I don't think 3 should be in range

There's less than a page of sellers on op, check if you don't believe me

Anything over 2.66 is to show there's demand for this and people are willing to pay a lot