I saw the other suggestion this morning, and then I had my own look through OP. The other suggestion’s close, but the price should be in keys (what these are actually traded in), and 1-1.5 keys presents a slightly more accurate version of the market. This suggestion will also have proof.

Sold for Lower Range

http://www.tf2outpost.com/trade/7350963 - Sold for 1 key

http://www.tf2outpost.com/trade/7310008 - Sold for 1 key

http://www.tf2outpost.com/trade/7377744 - Sold for 1 key

http://www.tf2outpost.com/trade/7325036 - Sold for 1 key

Sold for Midrange

http://www.tf2outpost.com/trade/7357963 - Sold for 1 key + a ref

http://www.tf2outpost.com/trade/7234978 - Sold for 3.55 ref

http://www.tf2outpost.com/trade/7262846 - Sold for 1 key + 1 scrap

Sold for Upper Range

http://www.tf2outpost.com/trade/7177968 - Sold for Nice Key (1.5 keys)

http://www.tf2outpost.com/trade/7339858 - Sold for 1.5 keys

http://www.tf2outpost.com/trade/7190369 - Sold for 1 Naughty Key (1.5 keys)

http://www.tf2outpost.com/trade/7333256 - Sold for 1. 5 keys

Unsold for Higher

http://www.tf2outpost.com/trade/7372903 - Unsold for 1 key + 1.66

http://www.tf2outpost.com/trade/7359030 - Unsold for 1 key + 1.66

http://www.tf2outpost.com/trade/7381590 - Unsold for 5 ref

http://www.tf2outpost.com/trade/7368628 - Unsold for 5 ref

Unsold for Current Price

http://www.tf2outpost.com/trade/7349792 - Unsold for 2 keys

http://www.tf2outpost.com/trade/7317253 - Unsold for 2 keys

http://www.tf2outpost.com/trade/7257043 - Unsold for 2 keys

http://www.tf2outpost.com/trade/7360301 - Unsold for 2 keys

http://www.tf2outpost.com/trade/7378250 - Unsold for 2 keys

http://www.tf2outpost.com/trade/7350408 - Unsold for 2 keys

It’s pretty obvious that 1.5 keys is the upper limit if you want to sell, and that the majority of trade happens in this range.

Let me know what you think :D