Geobase would have been my first suggestion but aside from the way the tiles are separated to relatively small areas, I have personally had many issues with the data itself. See our own wiki for more details.
If I remember correctly then 1 arc-seconds (about 30m resolution) (SRTM1) coverage only includes continental US in and parts of Canada but does not include all of BC. 3 arc-seconds (90m resolution) (SRTIM3) does include all of BC. Some provinces have their own data warehouses. In Ontario it's LIO - Land Information Ontario from which users can obtain 20m resolution DEM for the entire province up to the 51st parallel, 10m resolution for Southern Ontario. I remember purchasing data for BC in the past but I don't think government spatial data in BC is free. You can purchase 25m resolution (USGS DEM standard) here.
Alternatively you can download all available SRTM1 and 3 data directly from USGS
I found downloading SRTM3 from USGS and mosaicing all of the province of Ontario wasn't as much work as I anticipated but it still takes a while to download all the individual files.