In the U.S. I did not find it difficult to find places to buy watercolor supplies, especially online. National chains Blick, Cheap Joe’s, and Jerry’s Artarama are common and do a lot of online business, and regional specialty stores like St Louis Art Supply or Wet Paint Art in St. Paul, MN are also good enough to be worth ordering from even if you live far away.
In Canada, I have found it difficult to source the good stuff. There are fewer giant chain art stores and those that exist carry smaller selections at higher prices. However, I have poked around carefully and found some specific sources for the specific brands, colors, etc. that I like. Here are some of the more promising art stores that ship nationally.

