Sold mine for a key a few days ago - http://www.tf2outpost.com/trade/20022471

Any more sellers at 7? This thing is a bitch to sell at one, had to quicksell at 6.66 eventually but that was a while back

Add the CLASSFIELDS to your suggestion, so many sellers at 6-7 ref, that should help you proof your suggestion

Hardly any unsolds at 7.5 - 7.6 ref (0.9 keys = 7.5 - 7.6 ref). However, the proof in favor of your suggestion is pretty good.

Additional proof

http://www.tf2outpost.com/trade/20238536 - Asking 7.33, young

http://www.tf2outpost.com/trade/20225709 - Asking 7, young

http://www.tf2outpost.com/trade/19477418 - Unsold for 1 month at 7.66 ref (still values 7.66 ref as 1 key) (This actually was listed under the OP's suggestion, but the 7.66 ref = 1 key is significant enough to re-post it)

http://www.tf2outpost.com/trade/20110955 - 1 week unsold at 7 ref

http://www.tf2outpost.com/trade/20159902 - 4 days old, poorly bumped, lowered price from 7.33 to 7 ref at some point

http://www.tf2outpost.com/trade/19358409 - 1 month unsold at 7 ref, might be poorly bumped

http://www.tf2outpost.com/trade/20202686 - Got impacient trying to sell at 7 ref, sold for 6 ref

http://backpack.tf/classifieds/search/id/52c899374cd7b877188b456b - Sellers at 6 - 6.66 abound in the classifieds

If this looks like cherry-picking proof, I would like to point out that I looked specifically for listings at less than 1 key, because the OP lacked in that proof. There are the occasional sales made at 1 key, but these are the merchants and sorts of people who sell high anyway, so I'm not concerned about them.