The engine I know of that was built, was just over 20G (canadian) all said and done. Yes. That's expensive. But its an over 800 horse all aluminum small block. Naturally aspirated.
Look at other crate engine offerings. Chevy? Sure you can get 700+ horse engine from them too. Also 20 grand. Blue print? They make a supercharged engine making 750 horse, also 20 grand. Edelbrock, yup 20g. Pretty much anything close to 800 horse is 20g. And that's chevy. We know how lucky those guys are for how cheap everything is. What about ford? I couldn't find any crate engines (quick summit look) that made over 600 horse. Typical lol.
So really. It's not that out there. Gotta pay to play.