Almost everything you want for Reef chems is available at Univar. Last year I bought Dead Sea Works Magnesium (aka MagFlakes) ~$50 bucks for 50lbs. They had to special order it in for me in Calgary but I'm thinking they'll do the same in Vancouver. Dow Flakes is only $30 bucks. Sodium bicarb in USP # 1 is also available for ~$1.44 KG @22.7Kg bags (I opted for Arm and Hammer instead because carry 3 50lb bags home in one shot would have been a killer). And while you're at it, ask if they carry any GFO chemicals such as Bayoxide E IN-20 (used in water treatment plants)...don't know if it's possible but why not ask and you can do away with the expensive Rowaphos.
So there you have it, CaCl, MgCl, NaCO3 all in one shop
Good luck