Yeah, I think there should be a few books in a "free tier" section. Maybe very popular books like the 4 Hour Workweek or Lean Startup.

Then leave the rare content for membership tier. There is a 7 day trial, but it's a huge turn off as I'd just procrastinate and never look at it properly.

Blinkist would put their low quality books in the free tier, which was also a turn off.