Sounds like a good plan but make sure you get a radio with an "auxiliary input" as when away from shore it is nice to be able to plug in an MP3 player or smart phone without having to carry a stack of CDs. Most automobile radios accommodate speaker connections (4) for front and back with a fade function. You can install 2 waterproof speakers in the cockpit and perhaps get two higher quality shelf speakers for inside the cabin. When choosing speakers watch the power rating of the radio and the recommended impedance for the speakers. Do not be afraid to drill holes for speakers in the hull and being waterproof they will last for many years. I have to say I have enjoyed the cockpit speakers the most as that I what I listen to when sailing or just lounging. I'm on my second radio now but still on the first set of speakers. Sony, Kenwood, Pioneer all make good affordable automotive radios. I would avoid a set sold with speakers and would prefer to select my own. Eventually with the heat and humidity inside an enclosed boat cabin they will fail but should give you in excess of 5 years of service. When coastal cruising we listen to strong signal FM stations and when in the mood for particular type of music we connect a Tablet loaded with different albums. The sounds of the sea tend to drown out defined highs and lows as well as imperfections so there is no need to get extra high quality speakers for the cockpit. Just make sure they are waterproof and of good quality for durability. I don't know if they still sell $50 radios but most manufacturers have units starting at $79 which are quite adequate. Some have remotes which are very convenient to operate the radio without leaving the cockpit but I find these remotes and their batteries do not last long in boats so I would not give that any consideration.
