This is a discussion on Interesting New Books within the online poker forums, in the Learning Poker section; There looks to be a lot of interesting new books either realized or being released soon. It's too bad its tough to find fulsome reviews.
Nice list of new books. I don't think there's a site besides Amazon that will do better for reviews, but one option is to read the sample for any that have a Kindle version. (You can read these either on a Kindle or on a computer app.) Then you get a decent idea of the book without having to pay first.
For the others, if there aren't many reviews and no sample text, I agree that $30+ is a big ask!