I might as well make my own suggestion with all of the research I made trying to find counterproof/proof for the other suggestion.

1.1 keys~1 key+0.44 ref (~5.77 ref)

1.3 keys~1 key+1.55 ref (~6.88 ref)

Only one serious buyer I could find:

Bought many for 6 ref (not buying atm)

http://www.tf2outpost.com/trade/11120557

Classifieds will speak for themselves

http://backpack.tf/classifieds/search/5636/600/0

Sold

http://www.tf2outpost.com/trade/11166186 1 key+1 ref

http://www.tf2outpost.com/trade/11244927 1 key+1 ref

http://www.tf2outpost.com/trade/11219498 1 key+1.33 ref

http://www.tf2outpost.com/trade/11233585 1 key+1.66 ref (~1.3 keys)

http://www.tf2outpost.com/trade/11146197 1 key+1.77 ref (~1.3 keys)

http://www.tf2outpost.com/trade/11237261 mid-bp.tf (1.3 keys)

Selling 5.33 ref

http://www.tf2outpost.com/trade/11297638

http://www.tf2outpost.com/trade/11298701

Selling key+rec

http://www.tf2outpost.com/trade/11337591

Selling 6 ref (key+0.66 ref)

http://www.tf2outpost.com/trade/11230708

http://www.tf2outpost.com/trade/11325450

http://www.tf2outpost.com/trade/11326797

http://www.tf2outpost.com/trade/11354223

http://www.tf2outpost.com/trade/11355307

http://www.tf2outpost.com/trade/11356778

http://www.tf2outpost.com/trade/11360408

http://www.tf2outpost.com/trade/11366198

http://www.tf2outpost.com/trade/11367463

Selling 1 key+1 ref (~1.2 keys)

http://www.tf2outpost.com/trade/10934311

http://www.tf2outpost.com/trade/11020008

http://www.tf2outpost.com/trade/11206345

http://www.tf2outpost.com/trade/11265432

http://www.tf2outpost.com/trade/11283211

http://www.tf2outpost.com/trade/11285704

http://www.tf2outpost.com/trade/11296932

http://www.tf2outpost.com/trade/11328645

http://www.tf2outpost.com/trade/11334247

http://www.tf2outpost.com/trade/11336010

http://www.tf2outpost.com/trade/11337530

http://www.tf2outpost.com/trade/11342856

http://www.tf2outpost.com/trade/11348971 6:7

http://www.tf2outpost.com/trade/11354174 5:6

http://www.tf2outpost.com/trade/11356889

http://www.tf2outpost.com/trade/11357138

http://www.tf2outpost.com/trade/11360119

http://www.tf2outpost.com/trade/11361399

http://www.tf2outpost.com/trade/11364705

http://www.tf2outpost.com/trade/11365457

http://www.tf2outpost.com/trade/11365684

http://www.tf2outpost.com/trade/11366352

http://www.tf2outpost.com/trade/11367480

http://www.tf2outpost.com/trade/11370240

Selling key+1.33 ref (~1.25 keys)

http://www.tf2outpost.com/trade/11200489 4:5

http://www.tf2outpost.com/trade/11241016

http://www.tf2outpost.com/trade/11251249 4:5

http://www.tf2outpost.com/trade/11281384

http://www.tf2outpost.com/trade/11301288 4:5

http://www.tf2outpost.com/trade/11323363

http://www.tf2outpost.com/trade/11323429

http://www.tf2outpost.com/trade/11339658

http://www.tf2outpost.com/trade/11352224

http://www.tf2outpost.com/trade/11359125

http://www.tf2outpost.com/trade/11362877

Not sold slightly above 1.3 keys

http://www.tf2outpost.com/trade/11173639 6 days (3:4) 

http://www.tf2outpost.com/trade/11233585 4 days (key+1.66 ref) 

http://www.tf2outpost.com/trade/11234088 4 days (7 ref)

http://www.tf2outpost.com/trade/11319447 1 day

http://www.tf2outpost.com/trade/11338207 1 day

http://www.tf2outpost.com/trade/11351605 <1 day (3:4)

Not sold 1 key+2 ref (~1.4 keys)

http://www.tf2outpost.com/trade/11108692 1 week

http://www.tf2outpost.com/trade/11070422 1 week

http://www.tf2outpost.com/trade/11189862 6 days

http://www.tf2outpost.com/trade/11227043 4 days

http://www.tf2outpost.com/trade/11233398 4 days

http://www.tf2outpost.com/trade/11236316 4 days

http://www.tf2outpost.com/trade/11267160 3 days (26 views)

http://www.tf2outpost.com/trade/11280038 3 days

http://www.tf2outpost.com/trade/11285593 2 days, added

http://www.tf2outpost.com/trade/11309111 1 day

http://www.tf2outpost.com/trade/11328197 1 day

http://www.tf2outpost.com/trade/11331012 1 day