http://backpack.tf/classifieds/search/id/5283842e4dd7b859518b4568

Lots below 1.5 keys, everything upwards is apparently not moving.

http://backpack.tf/classifieds/search/id/521d4d2fba2536591f8b4567

Also, it's extremely easy to find a strangifier at or below 1 key.

Unsolds at above 1.5 keys (people aren't even trying, so number is limited):

http://www.tf2outpost.com/trade/15782105 - 1 week (2 keys)

http://www.tf2outpost.com/trade/15806095 - 1 week (2 keys)

http://www.tf2outpost.com/trade/15830758 - 6 days (2 keys)

http://www.tf2outpost.com/trade/15877994 - 3 days (2 keys)

http://www.tf2outpost.com/trade/15844386 - 4 days (2 keys)

http://www.tf2outpost.com/trade/15923029 - 5 days (2 keys)

The only 3 solds that can be found are at ~1 key:

http://www.tf2outpost.com/trade/15905872 - 1 key

http://www.tf2outpost.com/trade/15905790 - 1 key

http://puu.sh/5sxPO.png ~ 1.5 keys (rather uncertain)

Selling/sold:

http://www.tf2outpost.com/trade/15835952 - 1 key

http://www.tf2outpost.com/trade/15948988 - 1.5

http://www.tf2outpost.com/trade/15893701 - 1.2

http://www.tf2outpost.com/trade/15775557 - 1 key

http://www.tf2outpost.com/trade/15901917 - 1.3

http://www.tf2outpost.com/trade/15944395 - 1 key

http://www.tf2outpost.com/trade/15819206 - 1.5

http://www.tf2outpost.com/trade/15939794 - 1 key

http://www.tf2outpost.com/trade/15867156 - 1.5

http://www.tf2outpost.com/trade/15864216 - 1 key

http://www.tf2outpost.com/trade/15934664 - 1.3 keys

http://www.tf2outpost.com/trade/15901395 - 1 key

http://www.tf2outpost.com/trade/15855368 - 1 key

http://www.tf2outpost.com/trade/15760454 - 1 key

I'm being conservative, putting this at a key flat might not be a good idea.