With my goal of completing the 2003 Atomic set that I bought a box of last month, I noted there really weren't a lot of singles at the usual suspects. So, I instead hit up abd cards to pick up a few cards from the 3 down game. The website wasn't much, but I had no problem placing an order. If you're looking for players from your alma mater or other themes, they're recommended.
Again, if you're looking for CFL cards from the era where singles were plentiful (read: before the past few years when they became SP'd into a set-only release), check them out!