A lot of pot luck involved, both from the point of view of what kind of boat you want to play with and how much you are prepared to spend on it. Fully RTS boats are almost invariably built and equipped down to fit a price, very few get past the profile. Usually, it is the radio where the main economies have landed. A great many of those carrying optimistic artwork fall into the "use once only" category, especially if the chosen lake is salt water.

You could visit a model boat show with a bring n buy stall, but that generally needs a lot of luck to get a complete working outfit that doesn't need some work.

You will probably find someone in the club who has a model for sale. The chances are that you will get a much better boat, with better equipment and for less money than a RTR boat. I wouldn't advise buying from eBay or similar, because an inexperienced buyer can end up with problems.

Chas