I know it's pretty easy to find 1 for 3 but it's also possible to sell at more

Proof:

http://www.tf2outpost.com/trade/11945305 - MANY recent offers of 3, seems to be untaken

http://www.tf2outpost.com/trade/13908348 - Sold for 3 fast

http://www.tf2outpost.com/trade/14131861 - Sold for 3 in less than 2 days

http://www.tf2outpost.com/trade/14035147 - Sold for 3 in less than a day

http://www.tf2outpost.com/trade/13867316 - Sold some for 3

http://www.tf2outpost.com/trade/13545944 - Sold 37 for 3

http://www.tf2outpost.com/trade/14035115 - Sold for 3.11 in less than 2 days

http://www.tf2outpost.com/trade/7183759 - Offer of 3.33 pure and Strange Spy-cicle (1.33 - 1.66) + 1.77 which is 3.11 - 3.44

http://www.tf2outpost.com/trade/13771032 - Many offers of 3, 3.33 and 1 key 2 rec for 2 (3.33 each)

http://www.tf2outpost.com/trade/10045127 - Sold many for 3.44

http://www.tf2outpost.com/trade/12668665 - Offer of Genuine Awper Hand, 4 at the time

http://www.tf2outpost.com/trade/14179487 - Sold at 4?

http://www.tf2outpost.com/trade/14140614 - Sold many for 3.77, From the history of the 8 Grenades 2 or 3 are in different owners, 1 of them wrote added and he also sold some to: http://www.tf2outpost.com/backpack/115432

http://www.tf2outpost.com/trade/13575960 - Sold Festive Huntsman (3.33 - 4) + Festive Grenade for Black Genuine Anger (4 ref unpainted) + Triad Trinket (2.33, unless G version which is 5) + Strange Spy-cicle (1.33 - 1.66) with Dominations and Revenges parts - which puts Grenade at REALLY HIGH Value, it's an outlier but still someone paid that

3 ref is very possible but it usually sells really fast and above 3 is also possible