If you go to the kool stop site and click on "products," you will notice two options: unthreaded posts with pads (like the City and Eagle2) and unthreaded posts with holders (shoes) for pads.

Getting the holders will make it far less expensive to replace the pads later.

I would check ebay. There might be a non-kool stop holder out there that's less expensive than a kool stop offering but still allows you to mount kool stop replacements in the shoe.

Also search for used cantilever brakes on ebay with the holders attached. This might save you money. True story.