Waterproofing suede boots and canvas sneakers?

I just got a new pair of black suede boots, and I'm wondering where I can find waterproofing sprays? I know they have them at shoe stores, but which ones? Also, I know about how it may darken suede, but since they are black, it doesn't really matter.[or does it?] I was also wondering if you can use the same spray on a pair of canvas sneakers[my black chucks] Will it still work effectively?