[cypher]

Keeping pairs or groups is difficult & very stressful, I would recommend just keeping to single hams, that doesn't mean you can't have more than one but just not in the same cage, if you do decide to keep a pair then I would do lots of research into their requirements first.
I think you need to research into breeding too before you even consider it, you need to learn about genetics & how to care for mother & pups.
If you're going to pet stores for your hams then you won't get a campbell or WW, all pet shop Russians are hybrids & breeding hybrids can result in a lot of problems, mothers may die giving birth & pups can have many health problems.
Even if you went with robos you may end up interbreeding siblings which isn't good either, the only way to get into breeding once you've done the research is to get healthy pure bred hams from a breeder.