I'm probably behind the times but I just discovered Google Books which has huge previews (sometimes the entire book online) much nicer than Amazon's 5 page previews. I just stumbled upon this other day, so here's a link to a general search on Carnivorous Plants:
Anything that says limited preview can be viewed online, free. Which is wonderful since some books are simply missing the back cover or index, all the most important info is still there. It seems to return pretty good results with lots of reading material for almost any book / author / topic search.
Here's another couple online book places which has all full books, plenty to read if you have varied interests:
Hopefully this isn't old news for everybody since I just found out about it myself. Enjoy!