I made this search engine: https://www.gigablast.com/ that seems to fit that bill. As I am really the only programmer on it, my budget is essentially non-existent, therefore not allowing for many of the fancy additions you mentioned. The two biggest problems are 1) small index (need more servers) and 2) synonyms. The synonyms get pretty wonky sometimes, and often I miss good synonyms that I should be getting. But I don't have query logs like Google to use for synonym generation.

Also, I probably should have quit developing this years ago, I know, but it is an obsession. :)