That's the coolest thing about credit cards, you can call someone up, tell them what you want, confirm the design by email, and then it comes in a box delivered by UPS. You never have to know how much you spent on something that arguably does nothing for power or performance, other than possibly increase life. Of course, there's no real proof that it improves life either, since the engine wasn't previously damaged by running the stock hood.
It's all a wash in the end... spend it on fiberglass, brake pads, track time, doesn't matter... it's all just money spent on trying to stay ahead of the next guy or gal....
But to answer your question, it all depends how they set up the original molds for the hood. If they can't blank the center sccop to get a flat hood, it would be pretty darn expensive. If they can blank the center scoop, resulting in a flat hood, grafting in the NACA ducts is pretty easy.
Of course, this is assuming that the intake duct is far enough back that the duct doesn't end up on the leading edge of the hood. If that happens, we'd have to figure something else out. Basically though, I'll be looking mostly toward getting more air passing over the turbo. It won't help power at all, might even hurt it some, but I hate cooking things under the hood, been there, done that, lost the race....