Yeah you should be able to. Just ask them for a pinkie, its a newborn hairless mouse. They should be pretty cheap too, like a dollar. I havent kept any gophers for any significant period of time but I have heard that they go on "off feed". This means they may suddenly reject food for a period of about a month, and then regain normal eating, just for a heads up. If the snake is aggressive, do not worry. The young gophers are generally more aggressive in my experience, larger gophers seem to be more tame. I note this from coming across them in the wild, we take measurements but dont keep them at this time due to lack of space.