Let's start of with the support proof as always.

Classifieds AS OF THE POST OF THIS SUGGESTION:

x1 at 4.38 Keys. ( http://i.imgur.com/LEfa78N.png )

x3 at 4.5 Keys. ( http://i.imgur.com/QPuYllj.png )

x1 at 4.63 Keys. ( http://i.imgur.com/2EAmj8R.png )

Selling for less than 5 Keys:

http://www.tf2outpost.com/trade/19949865 - 4 Keys and 3 Refined Metal. - AUTOBUMPER.

http://www.tf2outpost.com/trade/19948174 - 4 Keys and 4 Refined Metal(4.5 Keys).

http://www.tf2outpost.com/trade/19932439 - 4 Keys and 4 Refined Metal(4.5 Keys) - 1 Day old - AUTOBUMPER.

http://www.tf2outpost.com/trade/19891047 - 4 Keys and 4 Refined Metal(4.5 Keys) -4 Days old.

http://www.tf2outpost.com/trade/19753264 - 4 Keys and 4 Refined Metal(4.5 Keys) - 1 Week+ old.

http://www.tf2outpost.com/trade/19697717 - 4 Keys and 5 Refined Metal - 2 Weeks+ old - AUTOBUMPER.

http://www.tf2outpost.com/trade/19300332 - 4 Keys and 7 Refined Metal - 1 Month+ old.

Unsolds at 5 Keys.

http://www.tf2outpost.com/trade/19890974 - 4 Days old - 5 Keys - Unsold.

http://www.tf2outpost.com/trade/19581179 - 2 Weeks+ old - 5 Keys - Unsold - AUTOBUMPER.

http://www.tf2outpost.com/trade/19877063 - 4 Days old - "bp.tf price" - Unsold.

The rest are 6+ Keys each.

Incase some people are bad at math, 4.5 Keys= 4 Keys and 4 Refined Metal.