I am also one of those Canadians with limited ability to easily shop for accessories. I took some advice from others and made up this little rig and thought I would post up some pictures in case others wanted to try a cheap alternative to internet shopping/shipping/taxes/duty on a diffuser. I did up the "iron fry pan with handle cut off" trick.
I went to Home Depot and bought a couple stainless steel rods for around $7. I cut them and bent them to hang over the fire box.
I picked up a cast iron frying pan at the Great Canadian Super Store for $14 and cut the handle off with a grinder. I think it was an 11" pan. It sits level on the rods and rocks back and forth but does not fall off.
As you can see, it sits in between the coals and the lower grill. I put apple juice and water in it for a pork shoulder "low and slow" but it just boiled dry and ended up catching all the fat drippings. You could keep it topped up though if you tended it. I don't bother anymore; I just use it as a diffuser and it works great.
Here is my first 14hr "low and slow" with two bone-in pork shoulders. They were the best I have ever made.
I first tried using a pizza tile instead of the iron pan. The extreme heat broke the tile almost perfectly in half. I use the half now on the lower rack when I want a nice indirect setup and move stuff onto the upper rack above it to cook after being seared. That works well too. I bought a new pizza tile and use it on the upper rack with the pan diffuser in place to do pizza and the results are fantastic.
