I've personally spent 2 weeks to sell a pink one for the backpack suggested price, and I ended accepting an item offer.

PROOFS:

http://www.tf2outpost.com/trade/19403471

http://imgur.com/FHM05ye

Wharehouse sells it for 65.700 credits (2.86 keys), and is currently full stocked. I think it's quite important, because it buys for less, and that means there were sellers for above that price.

http://www.tf2wh.com/item/766/6/5b8caac9987f692dbfabb0ac96de88dd/doublecross-comm

Unsolds for actual price:

http://www.tf2outpost.com/trade/19676571 (4 days)

http://www.tf2outpost.com/trade/19577027 (1 week)

http://bazaar.tf/trade/800975 (3 days, pink)

http://www.tf2outpost.com/trade/19649688 (6 days)

http://www.tf2outpost.com/trade/19500484 (2 weeks)

http://www.tf2outpost.com/trade/19753440 (painted, high price)

http://www.tf2outpost.com/trade/19685961 (free paint)

http://www.tf2outpost.com/trade/19566840 (black, 1 week)

http://www.tf2outpost.com/trade/19685335 (3 days)

http://www.tf2outpost.com/trade/19048578 (1 month)

http://www.tf2outpost.com/trade/19704157 (2 days)

http://www.tf2outpost.com/trade/19632396 (one week, painted TS)

http://www.tf2outpost.com/trade/19552214 (black, one week)

http://www.tf2outpost.com/trade/19689401 (black, 3 days)

http://www.tf2outpost.com/trade/19682927 (black, 3 days)

http://www.tf2outpost.com/trade/19702511 (cream spirit, 2 days)

http://www.tf2outpost.com/trade/19709658 (2 days)

SOLDS:

http://www.tf2outpost.com/trade/19396480 (first offer, one week ago)

http://www.tf2outpost.com/trade/18682670 (third accepted offer, one month ago)

He bought some Doublecross Comms at good price http://www.tf2outpost.com/trade/18923883

As backpack.tf is meant to give a spreadsheet of prices at wich an item would be possible to sell in a reasonable amount of time, the price should be reduced in my opinion. Anyway, it's my first suggestion, based principally on my own experience, as this item is being traded as far as I've seen only by full-price (un)sellers and quickbuyers. I tried to find other evidences, and I'll gladly accept any suggestion, proof and counterproof.

Why 2.8-3? 3 is the actual price, and it's not impossible, even being hard, to sell it for that price. 2.9 is not a reasonable change, nobody would care about a so little variation, while 2.7 is a too big change.