I did just that. Well not specifically aimed at research, but the types of websites I'm interested in, written by humans, blogs and such. It's got some quality issues right now because I fucked up some of the keyword extraction logic and it's taken a while to identify just what's gone wrong.
Even though it's a bit broken, it has some lucid moments. Just compare:
https://www.google.com/search?q=mechanical+keyboards
https://search.marginalia.nu/search?query=mechanical+keyboar...
The take-away I want to drive home is that it's absolutely possible to build something the scale of Google c.a. 2003 and run it on consumer hardware. I think, due to general difficulties in making these things profitable, the ideal approach is to make the operation so absurdly cheap it can be run non-profit instead. I'll gladly pay out of my own pocket to have a good search alternative.