The main question is the amount of work it would take to build your own search engine. I don't think you should worry too much about the need for alternative search engines. With the same argument, you could say there is no need for any other store because there is Walmart, but that's not the way it works, people like diversity. On the other hand, there must be an argument to attract a cross-section of web users. Privacy could be such an argument, but from what I read here and there, it may be difficult to implement in the US because of something called the patriot act. You probably know much more about this than I do. Even without this, people may be attracted by the idea of not being tracked by Google, Microsoft, Facebook and other giants who'd like to know everything we do online. There could be other attractive arguments that you need to discover. Then you could inject a percentage of links to your product.