More than 1.5 cents per search is a lot, they're pricing model really discourages me from making them my default search engine. A $10 unlimited search would be more justifiable. $15 would be stretching it.
If I'm not on a functionally unlimited unlimited plan (rate limiting is fine if it's reasonable) then I have to think about it every time I search. Should I really be searching here or should I be using the search box on stackoverflow or github or Wikipedia? Just introduces some constan cognitive frisson to the experience.
There is Ultimate which is not capped. That seems to be what you want?
Personally, my record was below 900 searches and usually below 800, so the 1000 searches (technically 1500 because early adopter) are absolutely fine for me.