While modern radios have computer chips in them, they're generally referred to as transmitters and receivers. A watertight box is a different matter, some people modify plastic WTY boxes sold for scuba diving, and others build WT boxes from wood/plastic/pasta/what-have-you. Others run their receivers waterproofed with no WT box at all. Searching for 'RC transmitter', '2.4GHz transmitter', or '75MHz transmitter' might give you some results that are useful.
