First off, you're not going to find or build a COMBAT LEGAL SHIP for less than three times the money you are looking at spending. Between buying or building a legal semi-scale hull with superstructure, installing the drive system with all the batteries, speed controller, motors, etc, the multichannel radio to control the ship as well as the gunnery system and, last but not least, the guns themselves, you could be looking as high as $2000+
Since I don't know where you're located, I can't send you to any one club or person, I'm going to direct you to this other website for further information:
rcwarshipcombat.com