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 10 Keys - http://i.imgur.com/JTt5sq5.png

Unsold for 2 days http://backpack.tf/item/637867033

Unsold for 10 hours http://backpack.tf/item/639127712

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x1 for sale at 10.3 Keys(10.28) - http://i.imgur.com/R7gUkiE.png

Unsold for 1 day http://backpack.tf/item/643522966

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x1 for sale at 10.35 Keys(10.33) - http://i.imgur.com/8jrD8Ys.png

Unsold for 6 days, duped, "quicksell" http://backpack.tf/item/644356532

Buyers suggest 9.35 Keys and below is the quicksell/buy price: http://i.imgur.com/YYtPqVh.png

Outpost sellers.

http://www.tf2outpost.com/trade/28349391 - 10 Keys + 5 Refined - Unsold for 1 day.

http://www.tf2outpost.com/trade/28169575 - 10 Keys + 3 Refined - Unsold for 2 months.