You can find good used stuff for under $350 many times, but I would really strongly advise you not fly it at the beach. As stated earlier, it will trash the engine and radio stuff fairly quickly. I would find a club and learn with them. You will find that flying on the beach will not work really well. Maybe some day with the right stuff, but not a beginner. Sand in an engine will destroy it quickly. You would be wasting the money you spend because you would destroy the plane and engine very very fast.

Not saying that to discourage you, but if you want to fly and save money, a club and good instructor will help. Doing it on your own on sand is not a good idea. I would guess the plane wouldn't last 5 minutes before you pack it in and destroy the plane, and if you fill the engine with sand and turn it over, its toast too.