It was www.carparts.com. $67.99 USD + $11.99 for shipping to Canada. Their website says that shipping charge includes all taxes and customs, but UPS charged me $40 for brokerage. So I emailed carparts.com and asked what was up with that and they refunded me $40!!!!!!!! Talk about great customer service. So my total charge was $79.98 USD. The kit includes hoses and Schraeder valves, so all I had to buy extra were some zip ties to hold the hoses along the frame. I drilled little holes beside the tow ring in my rear bumper and put the valves there. As for the model of bags, they are called Air Lift 1000 and I just specified 1992 Montero. There only seemed to be one option.........

The only thing which isn't perfect is that you need to always keep 5 psi in them to keep their shape. Otherwise they could get pinched between the spring or whatever. So this 5 psi raises the rear end a tiny bit when the truck is empty. But it's rarely empty, so it doesn't matter that much. I think it's only about 1 cm anyway......