Do not purchase anything from the store under any circumstances... This only puts profits in the owners pockets keeping his doors open longer.
Stop in every Saturday (when they are the busiest0 and stand in front of the cage and talk to your friend about how awful it is they don't take proper care of their animals and how you would never buy anything from them because you don't believe in supporting such low grade standards...
Your welcome to try to talk them into doing a better job, but very very rarely will a shop owner or even employee happily accept constructive criticism from a shopper...
I feel it is critical to avoid "rescuing" animals that are kept in such conditions by purchasing them. While this does remove one animal from poor conditions it assures another one will be put in it's place, and also increases the stores profits ensuring the store stays open longer thus putting more animals into poor condition. So by purchasing such an animal, you are actually causing more animals to suffer...