There is a bunch (OK, relatively, anyways) of Canucks hanging around on the Pilkguns Target Talk forum. They would be able to give you a lead on suppliers of the cylinder. As should the Walther site, if they show the authorized dealers.
The pump you should be able to get from about any dealer that sells PCP airguns. D&L Airguns is one, there is a fellow in North Battleford(name escapes me at the moment) that deals in target airguns, as well as a few others abot the continent.
Don't hold back from searching around the world for your needs. Too few stocking dealers of this stuff to expect to find a walk-in source.
Cheers
Trev