I live in Iowa, so I can't answer for MD, however we are not offered free CNA classes here. In order to take one you need to pay out of pocket, or be employed by a nursing home or LTC facility (they pay the cost). Maybe you can look around and see if you can work at a LTC and get your classes paid for. Otherwise, here in IA you can challange the boards, if you already have CNA under your belt then you could do that and skip the class all together, would still cost you some money, but alot less then what you would pay with the class and state testing.
Hope that helps you!!!