"Selecting Resources" Delving Deeper

I LOVE selecting resources for unit/lesson plans.  In this delving deeper our group chose to select resources for a 2nd grade unit in weather patterns.  It was so interesting to research possible fiction and nonfiction resources to suggest.  I used my own 2nd grade colleagues as a resource (which was a HUGE help in getting started) AND I used Amazon, which probably isn't the most professional way to do this type of research, but I found it helpful to be able to use their feature to "look inside the book" Amazon's reviews, although not professional, are detailed and helpful (I think).  We're going to be talking about selection tools and acquisition in Dr. Moe's class soon so I'm sure that I'll learn the "proper" way to do this.  I will say that it is very difficult to make a judgment call on the "worth" of a resource without actually having it in my hand to evaluate.