What kind do you want to shoot?
First off, get you restricted and non restricted PAL. You can get this from The Shooters Edge. 1 Sunday, $200. Then you send in your app to the gov and then you can get any non restricted or restricted weapon out there. This will allow you to shoot handguns.
Ammo depends on what kind of weapon your shooting. I shoot a lot of military surplus weapons, such as the Russian Mosin-Nagant, SKS, German K98 etc. Ammo for these types of weapons is relativley cheap since you can most likley find surplus military ammunition.
I have a case of Czech 7.62x54r for my Nagant from the 60's. I think I got it off
www.marstar.ca and it was about $200 for the case of 800 rounds.
Also bought a case of 1200 rounds of 7.62x39 for my SKS. Runs abot the same, $200.
If you're not shooting military surplus, prices take a huge leap.
There is pretty much no surplus .303 brit. So if you had a Lee Enfield rifle, you'd pretty much have to buy new ammo, which is like $10 for 20 rounds.
You can buy ammo locally at a number of shops. I like Russell Sports, but there's places like Things Military that also sell ammo. But it really depends what kind of ammo your looking for. I find that crates of milsurp is best found online.
There are a few ranges around also. If you want to drive out to sibbald flats, you can use the public range there for free. No pass required.
Cheapest route for ammo would be reloading your own, as that can wind up costing just pennies per round. It just takes time and patience.
But also keep in mind that day by day, surplus rifles and ammo are getting harder and harder to find. Ammo is drying up and rifles are drying up. 15 or 20 years ago you could buy an unfired Enfield for $50 or $75. Now the more desirable ones are going for $800+. Some of these weapons can be an investment, but if you take good care of them, thay might make you some money some day.
A good board to read is
http://www.canadiangunnutz.com/
There is everything you could ever want to know about owning and shooting firearms in Canada on that board.
Any other questions, feel free to ask me.