I realized that there is not much proof for 1.4 keys, so a new suggestion.

Proof:

Unsold for 2 keys:

http://www.tf2outpost.com/trade/10813338 4 days

http://www.tf2outpost.com/trade/10710631 1 week

Unsold (other):

http://www.tf2outpost.com/trade/10837941 3 days, no offers

Unsold, but with eligible offers:

http://www.tf2outpost.com/trade/10067282 1 month, S. Degreaser (2 keys)

http://www.tf2outpost.com/trade/10793812 5 days, Last Breath (1.8-2 keys)

http://www.tf2outpost.com/trade/10444389 2 weeks, Festive Sticky (1.5-1.75 keys)

http://www.tf2outpost.com/trade/7119381 4 months, 2 keys

http://www.tf2outpost.com/trade/9200081 2 months, 2 keys

Young ones (2 keys):

http://www.tf2outpost.com/trade/10928608 20 hours

http://www.tf2outpost.com/trade/10947688 10 hours

http://www.tf2outpost.com/trade/10915245 1 day

http://www.tf2outpost.com/trade/10927290 21 hours

Young ones (lower):

http://www.tf2outpost.com/trade/10924954 22 hours, Robro + ref for 2 keys

http://www.tf2outpost.com/trade/10942546 13 hours, 9 ref

Sold ones (2 keys):

http://www.tf2outpost.com/trade/10841471

http://www.tf2outpost.com/trade/10274579

http://www.tf2outpost.com/trade/10274579

http://www.tf2outpost.com/trade/10731200

http://www.tf2outpost.com/trade/10861356

http://www.tf2outpost.com/trade/10933935

Sold ones (lower):

http://www.tf2outpost.com/trade/10330736

http://s14.directupload.net/file/d/3260/she2spxg_png.htm 7 ref

http://www.tf2outpost.com/trade/10275089

http://s1.directupload.net/file/d/3260/3br7jxao_png.htm painted one for 1 key + 2.33

Buyers for 2 keys:

http://www.tf2outpost.com/trade/10917795, 1 day

Bought one

http://www.tf2outpost.com/trade/10935126 1 key 4 ref

At the time of writing, these were the only confirmed non-quicksell/buy trades.

Feel free to add proof/counterproof, so we can make this suggestion better if so desired.

Thanks, WEGA, for providing proof http://steamcommunity.com/id/dimi151