Mine is temporary, so I had to pay for everything, technically I had insurance for most of it through work so they paid most of it. I'm getting it reversed in the near future, just waiting on a surgery date.
Yours is permanent the gov't allows you $600 a year this works out to roughly half the cost of basic supplies for the year. You can pick them up Shopper's Drugmart Home Health Care Centres (but not the regular Shoppers), Well.ca also sells them and there a few other places.
The hospital will most likely send you home with some, I got roughly a months supply, the hospitals in Toronto seem to go with Coloplast. They might also ask you if can give your info to one of the medical supply companies, if that is the case they'll most likely ship you another bunch of bags and what not.
You'll probably get at home nursing care, or at least they'll offer it to you. Mine was paid for by the OHIP, I assume yours will be too. If it's free take it. For about a month or so they come by a couple times a week to check on how things are going and they'll order supplies to leave onsite to look after your incision and ostomy. They might order more ostomy supplies for you, these will also be on OHIPs dime, if you get a nice one like mine was they might order extra. Plus, sterile saline, gauze, sponges, powders etc, my surgery was almost 3 years ago, and I still have some of the supplies my nurse ordered.
You'll get a basic "how to" set of instructions in the hospital, but the at home nurse will be the one to properly teach you if you are having issues, plus they'll be the ones to remove your staples.
Where are you in the province and where are you having surgery done?