Selling for less than 4 keys

http://www.tf2outpost.com/trade/20363328 - 3.67 keys

http://www.tf2outpost.com/trade/20726067 - 3.9 keys

http://www.tf2outpost.com/trade/20840421 - 3 keys

http://www.tf2outpost.com/trade/20853417 - 3 keys

http://www.tf2outpost.com/trade/20696063 - 20% x 4 keys = 3.2 keys

Classifieds

http://backpack.tf/classifieds/?item=Sight%20for%20Sore%20Eyes&quality=11&tradable=1&craftable=1

- 2 for 3.46 keys (round up to 3.5)

- 1 for 3.93 keys

Unsold at current price

http://www.tf2outpost.com/trade/20871560 - 2 days

http://www.tf2outpost.com/trade/20895570 - 1 day

http://www.tf2outpost.com/trade/20779989 - 5 days

http://www.tf2outpost.com/trade/19681770 - !!!!!!!1 month!!!!!!!!

http://www.tf2outpost.com/trade/20628704 - 1 week

Solds

http://www.tf2outpost.com/trade/18326065 - bought many for 3 keys

http://www.tf2outpost.com/trade/19723056 - 3 adds within the month (3 keys)

So, overall as we can see this needs a price drop, but it's gonna be difficult finding a suitable price, so I think that 3.5-4 is the best price because the majority are being sold within that range, and also the fact that anything that sells for 3 keys would be a plain,simple quicksell!