Going to base this out of the current sellers of the market:

4 on the market.

http://www.tf2outpost.com/trade/27519721 - Unsold @ 24 for 3 weeks, + several other trades http://www.tf2outpost.com/trade/27417299

http://www.tf2outpost.com/trade/26924348

http://www.tf2outpost.com/trade/27082033 - Unsold @ 28 for 3 months

http://www.tf2outpost.com/trade/27541163 - Unsold @ 28 for 2 weeks

http://backpack.tf/item/3915185152 No sales for the past 3 months

http://backpack.tf/item/4376790828 Immediatly quicksold for 22 keys after being bought off the market (04 Dec sale), not using

http://backpack.tf/item/4091460270 No sales for the past 3 months

http://backpack.tf/item/4145827656 No sales for the past 3 months

Credits to "Jack" for helping and "iN008 /aɪ⇄nuːb/" for pointing out the unsold #1

(don't ask me why it's in bold)