Can this be considered animal cruelty?

Assuming that the animals are kept this way 24/7 it is cruelty. It's also not safe to mix rabbits and guinea pigs. I'm getting the impression that this is a home breeding business, caring for these animals properly would cut in to their profits. Sadly situations like this aren't uncommon. It's why you should adopt or go to an ethical breeder for your pets instead of stores that are supplied by people like this.