I want to get some large clipless shoes for an indoor stationary cycle at my gym, which I presume uses SPD. I wear a U.S. size 15B and it is difficult to find shoes that long, let alone with a narrow width? Shoes I could source in Toronto, Canada, would be best, but I can get them in the U.S. if I must.
I feel your pain…
One place that I've found that seems to stock large shoes is Bike Tires Direct. Both Shimano and Sidi seem to make models that go up to at least size 52. If you don't want to order from the US, you could still use their listings to find some candidates and then ask your LBS what they can order for you.
The shoes will come in two styles "road" and "mountain." Road shoes have a flat sole that the cleat mounts onto (and thus are quite unpleasant to walk in). Mountain shoes have a recess for the clear. Road shoes often use different cleats than mountain shoes (three-bolt vs two-bolt). Cleats usually come with pedals, not with the shoes. You can also buy cleats separately.
So find out what kind of cleats your bike needs and then get shoes & cleats to match.