I recently found out that the Nintendo DS is going release software called "100 Classic Books" this week for $20. The software is exactly as it sounds. It's 100 pieces of classic literature like Hamlet, A Tale of Two Cities, Huck Finn, etc... all in one piece of software. The complete list is found here.
Nintendo DS Games - 100 Classic Books | E-Books to Download | Nintendo

"Wow!" I thought, "you can't beat that." Well I decided to look at what it would cost on the kindle and found that a large amount of classic books are already free on the kindle. For example, here is a free Alice in Wonderland download at Amazon.
Amazon.com: Alice's Adventures in Wonderland eBook: Lewis Carroll: Kindle Store

I may be alone in this, but I find it really amazing how accessible classic literature is now. In either of the above cases the cost is really in the hardware. Once you have that the literature itself is either really cheap or totally free. I suppose the major limiter is really the time it takes to read all of these books.