Buying NO3/K/PO4 by the pound

[Nemo]

Is there a place in ottawa where I can buy these macro fertilisers by the pound for my planted tank? The only place where I seem to be able to find them is at Ritchie Feed and Seed on Innes, but I have to buy 30+ Kg of each at a time!  

I had to resort to the pharmacy to get my KNO3, but it gets expensive.

[Nemo]

you can get KNO3 for about 6 bucks at any hydroponic store.

Anything in the west end area?
Thanks