Crazy idea, but it might work. Sometimes podcast guests recommend good books, and I happen to have hundreds of transcripts stored to some of the best podcasts (https://smashnotes.com). I don't expose full transcripts to public, as I've learned that almost no one actually reads them, but I could scan for book recommendations and send them your way.

Btw, I tried the API and it works! There's a small caveat, for anyone who might trying it too.

If you have an active Affiliates account with Amazon, and you qualify for the API access, it won't be enabled even when you get your key-pair. The API will throw a generic error "Too many requests."

You have to go to >Contact Us< section of the affiliate program and ask them to enable your access.