I've been buying books through iBooks on my ipod, but I've decided I want a bigger screen.

I looked up the Kindle, & books are a little cheaper through Amazon, but you can also get Kindle for the iPad. Not sure if its available through Android for tablets or not?

What do you use? Should I get a specific ereader? Or a cheap tablet with the possible higher book prices? Or try to get hold of a second hand iPad? I want a good battery life, so thinking an ereader is the better idea, but if I'm going to spend that kind of money I may as well get a tablet that I can do other things on?

I've not owned a kindle/ereader, so don't know what you can actually do with them?

Any suggestions? What do you use?