This is called a metasearch engine. There was kind of a golden age of metasearches, maybe the 80's or 90's, and an actual site metasearch.com, although if you go there now, it just redirects your search terms to Google. So think about who is the Google of metasearch nowadays, and I think the answer is harder to answer today than it has ever been.
Surfwax tries to do this but the results don't cut it for me. Perhaps metasearch fizzled out because most people figured out it's more efficient to figure out which search engine is best, and just use that instead of collecting all those results from different search engines. But that is just one man's opinion.
On the other hand, if you're offering the equivalent of the
X Prize to create the Google of Metasearch, for that much money someone, or more likely a team of someones, might come up with something truly excellent.
But what I really think is that a lot of people tried already, and that the results you get back are not going to be as useful as you think they are, unless you are capable of recruiting Google-class talent to tackle the problem.