A lot of people selling for 1 ref. 1.33 goes unsold.

Classifieds

http://backpack.tf/classifieds/search/741/11/0 - Several selling for 1 ref

Sold/Selling for 1 ref

http://www.tf2outpost.com/trade/7529035 - Selling for 1 ref

http://www.tf2outpost.com/trade/7612295 - Sold for 1 ref

Unsold for 1.11 - 1.33 ref

http://www.tf2outpost.com/trade/7493262 - Unsold for 1.11

http://www.tf2outpost.com/trade/7604028 - Unsold for 1.22

http://www.tf2outpost.com/trade/6034810 - Selling for craft hats, no posts in a month

http://www.tf2outpost.com/trade/7015413 - Unsold for 1.33

http://www.tf2outpost.com/trade/7644337 - Unsold for 1.33

http://www.tf2outpost.com/trade/7583871 - Unsold for 1.33

I found one outlier, but I think it's a bit of a quicksell and shouldn't be incorporated into the range just yet.

http://www.tf2outpost.com/trade/7417246 - Sold for 0.66

All in all, it's very hard to sell these at 1.33 and most have given up and switched to 1 ref.