Creedmore Sports is your answer.
http://www.creedmoorsports.com/shop/home.php
The Schuster plug is all you need. Get a couple of 2 round clips while you're at it.
I attended a CMP Clinic recently and learned a lot about the Garand System.
I run my plug all the way open so that the gun doesn't cycle and I don't have to chase my brass. however during Rapid Fire strings I simply switch the plug out for the stock plug and the gun functions normally.
You won't have any problem with standard M2 Ball ammo as it was designed specifically for the Garand. Don't run Factory Hunting Ammo meant for Bolt Action Rifles as the velocity is around 2900+ fps and the Garand is designed to function properly around 2700 fps. The dreaded "Bent Operating Rod" can be the result.
With the adjustable plug you can run this ammo and simply start with the plug all the way open and close it 1/2 turn at a time until the gun functions.
HOWEVER::: The best solution is to either run Surplus M2 Ball ammo or Reload to Garand Pressures. The current Hornady Reloading Manual has pages of loads specifically for Garands.
M2 ball ammo was primarily loaded with a 150 gr Spitzer bullet with from 46-49 gr of IMR 4895 powder. The differences in charge weights was due to the changes in different lots of powder as they were produced. Each new lot was tested and the charge adjusted until a specific velocity range was attained, then the run of ammo was assembled using that charge weight.
My standard .30-06 load is a 147 gr M80 Ball (.308/7.62x51) recycled bullet,,, with 45gr of IMR 4895. This has proven accurate and dependable and functions in my Garand perfectly. I run this same load in all my .30-06's, bolt guns and my .308 bolt guns too. (Same Load, Same Bullet, .308 case)
Obviously you probably aren't going to be able to attend a CMP Clinic in Canada, however there are literally hundreds of books and articles on running your Garand available as well as knowledgeable people at your local range.
Get into to reloading your own ammo as soon as possible. you'll shoot a lot more.
Randy