P&D in Edmonton sometimes gets in some of the Kent 2 1/2" shells. They usually sell out very fast, which does not seem to be an indicator that the orders should be larger (minor rant).
Anyways, you could do worse than to give them a call.
The gent in southern Alberta that sells the Yildiz (spelling?) Turkish Shotguns, also stocks and sells the supplies and a couple reloading books that cover off 2 1/2" shells.
I have been gathering together the stuff to load some, as I seem unable to get the timing right to buy any of the Kent loads.
Cheers
Trev