I don't really like candy buffets, a bit overdone, BUT that can only be good for a business as they're clearly really popular! I know loads of people do this sort of thing with great success. You'd have to have loads of different canister options though, like maybe some traditional jars and then some posh looking bowls and then something like vintage floral crockery, cos people love options and it makes you seem better overall as a company if there's choice. I don't think with candy buffets alone you'd make loads, just because you can't charge THAT much for them, but it's a nice starter or side business.
Oh and you could also maybe offer personal options such as jar labels that are unique to that wedding/reflect the couple or something?