RE: Kits or scratch plans?
Shawn, from what you want in a boat, I'd steer you toward getting the Wild Thing plans and blowing them up to about a 40" hull and sticking a mild .40 engine in it. It will have reasonable speed, won't need $30+ a gallon fuel or special glow plugs and will handle "rougher water". A rule of thumb in boat racing is speed = $$$$$$$$$$. True racing engines are expensive ($300ish for a .21 and more for a .45 or .67). Fuel for the monsters is expensive also. Not to mention the glow plugs that you'll consume just because of the nature of the engine. Your $300 to $400 target won't get you into that category anyway so stick with the Wild Thing and a reasonably priced engine. Enjoy the build and the satisfaction that you'll get when you have a boat you built. And it won't be the cookie cutter plastic toy that your neighbor has.