In reply to Indy:
I've just been through this. I am green as the grass so take my advice FWIW.
There are more than just two makers out there but the main ones seem to be "Look - Keo" and Shimano.
Then you have to decide if you are going for the mountain bike type (SPD) or the road bike type (SPD - SL).
Once you have decided that then there is a massive range in quality so you can pay from $50 CAD up to $450 CAD (you can convert the currency).
The quality difference is both in the machining, quality of material, quality of bearings etc. and in the weight.
So I went for a set of Shimano 105's which are a bit better than the entry level but not megga expensive.