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 - Unsolds and item histories are presented in chronological order according to the screenshot(s).

x2 for sale at 2.55 Keys - http://i.imgur.com/hIRt8gG.png

Unsold for 7 days http://backpack.tf/item/2078716524

Unsold for 2 days http://backpack.tf/item/2038179783

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x2 for sale at 2.7 Keys - http://i.imgur.com/rJb0zOg.png

Unsold for 6 days http://backpack.tf/item/2049286321

Unsold for 6 days http://backpack.tf/item/2078537565

Outpost sellers.

http://www.tf2outpost.com/trade/28374933 - 2.55 Keys - Unsold for 3 weeks.

http://www.tf2outpost.com/trade/28382118 - 2.7 Keys - Unsold for 3 weeks.

I am excluding all trades on Outpost that haven't been bumped for 1 day or more.