Don Knuth's volume 3 of TAoCP is fully dedicated to "Sorting and Searching" problems.
Building it yourself is the better option nowadays.
Start with open-source Meilisearch, and don't look back.
The "buy" options people talk about are tired-old snake oil, and you'll end up with buyer's remorse.
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we need to build
Why not buy?
If the company can buy, why isn't it?
If the company can't buy, it is under-capitalized and that's a sizable problem because search is a commodity.
Anyway, the best search experience is not needing to search for the same reason that I don't enjoy searching for my car keys when I am trying to commute to work.
Good luck.