I can't understand the $9 freight difference between WPX and KRN coz both the CP and CN railways just run across WPX plant site and the same to KRN. I know the WPX $59/ton freight includes rail and port cost but I am not sure the KRN freight includes port cost or not. Maybe that is the difference coming from.
For natural gas price difference, it is understandable because the gas pipeline is just sitting right by WPX plant. However, the gas pipeline is hundreds km away from KRN plant (WPX is only 35km away from city of Regina. KRN is about 200km away from Saskatoon). Of course gas company will charge KRN more than WPX.
For KRN sustaining cost, you can get it from KRN feasibilty study summary in their website.