You know I briefly looked in to it because I'm not dumb I understand it'd make this unstoppable, but there's very few options with very high prices. You never know with what the future holds but yeah, not cheap. Definitely doable though.

The good thing about 'our' filtering is that it would take down the number of daily requests to their API, but still...a. lot. I wouldn't say it's out of the question even remotely, I have the funds but am cautious with my finances/investments. But you're right and I should definitely give it some serious though..

That strikes me as a good option for a future "professional" tier of the website.

You could just pull number of google results as a proxy. You have the link to the google search now, being able to sort or filter by that would weed out a lot of junk.

Would also be nice to sort/filter by Wayback hits.

PR matters less these days but if you're going that route then maybe also pull Alexa, Ahrefs and Moz and the like (I've got a complete list somewhere)