Great to hear that you are exploring the non dead tree alternative. I'd love to hear your thoughts on going pbook free in a few weeks/months. Are ithers around you doing the same, but using tablets instead?
Though much less sexy of a device, the
Kindle DX has fallen to a low price of $239, which you could also return if it doesn't work for you.
The advantage would be the larger screen.
Ectaco also makes large ereaders, even color e-ink ones that you can write on, but they are much more expensive and, from what I've heard, their software has much to be desired, but users on the Jetbook forum may be able to tell you more about it - I could just remember it wrong.
The Jetbook color 2 is a steep $500 but may pay for itself over time if you use it every semester. It seems perfect for textbooks, since you can hand annotate and have color.
See all their readers here.