Counter suggestion.

Judging by both the Classifieds and Outpost, buyers suggest ~3.6-3.5 Keys and below is a quickbuy/sell price.

Classifieds at the time of posting this suggestion.

Unsolds are based on how long the listing has been up; Listing has been up 5 days and item been in the sellers inventory for 8 days? It has been unsold for 5 days.

The age of the listing(s) are shown in the screenshots rather than the last bump.

x2 for sale at 3.67 Keys, rounded off to 3.7 Keys - http://i.imgur.com/E8hUZKJ.png

http://backpack.tf/item/4505495240 - http://backpack.tf/item/4907971152

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x2 for sale at 3.72 Keys, rounded off to 3.7 Keys - http://i.imgur.com/rABSk8W.png

http://backpack.tf/item/4477061491 - http://backpack.tf/item/4473769862

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x2 for sale at 3.78 Keys, rounded off to 3.8 Keys - http://i.imgur.com/Tt4y7L0.png

http://backpack.tf/item/4301477193 - http://backpack.tf/item/4752796234

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x2 for sale at 3.82 Keys, rounded off to 3.8 Keys - http://i.imgur.com/ZlUZB2y.png

http://backpack.tf/item/4421723357 - http://backpack.tf/item/4243955976

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x1 for sale at 3.84 Keys, rounded off to 3.85 Keys - http://i.imgur.com/PxjV6OV.png

http://backpack.tf/item/4262234469

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x9 for sale at 4 Keys - http://i.imgur.com/LG6jsQx.png - http://i.imgur.com/oTI6ik4.png

Unsold for 13 days http://backpack.tf/item/4463148117

Unsold for 3 days http://backpack.tf/item/4418938425

Unsold for 5 days http://backpack.tf/item/4309974160

Unsold for 8 days http://backpack.tf/item/4217462309

Unsold for 2 days http://backpack.tf/item/4251634412

Unsold for 6 days http://backpack.tf/item/4440001585

Unsold for 4 hours http://backpack.tf/item/4224381031

Unsold for 5 hours http://backpack.tf/item/4382729165

Unsold for 15 hours http://backpack.tf/item/4316384636

Outpost sellers below 4 keys.

http://www.tf2outpost.com/trade/28347137 - 3 Keys 9 Refined(3.6 keys).

http://www.tf2outpost.com/trade/28351126 - 3 Keys 12 Refined(3.67 Keys) - Rounded off to 3.7 Keys.

Outpost unsolds at 4 keys.

http://www.tf2outpost.com/trade/28350150 - 4 Keys - Young - "willing to discount these items".

http://www.tf2outpost.com/trade/28337216 - 4 Keys - Unsold for 5 days.

http://www.tf2outpost.com/trade/28324538 - 4 Keys - Unsold for 1 week.

http://www.tf2outpost.com/trade/28314722 - 4 Keys - Unsold for 2 weeks.

Price is rounded off to the nearest .05