I know it may seem easier to carry around e-books, but I personally wouldnt recommend it. May I suggest an alternative? From my experience, I started NS not knowing that these books would be a part of me life, so I rented my first batch which was a big mistake since it already had markings all over it to distract me from what I thought would be important. And second, I would end up doing my own markings on the page with highlights, and personal mnemonics for that particular part of the reading. Having a physical book in hand, you can go go through the pages you need to refer to much quicker (IMO.)
If you want to reduce the strain on your back, I suggest taking your books to a local FedEx Kinkos, where they can cut the spine off your book and drill holes in it. The textbook can then be placed into a 2-3" binder to keep at home, and take out only the necessary pages for your class. I place the reading material in 1/2" binders and add on any handouts, and review notes I've made for that unit. My bag is very light this way. We have a unit exam every month, so after each exam, I transfer the contents into a separate 2" binder which ends up being my Final exam study binder. Its got everything we've studied, all the notes, and handouts for the entire semester all in one place-- instead of having to dig back. This is probably the best benefit to me.
So in short, I work the semester with 3 binders.
1) To place my textbook 2-3"
2) Place for my assigned reading material/handouts/notes 1/2"
3) Final exam binder 2"
It seems like a lot, but in the end, I think the act of clearing out my unit binder for the new material psychologically refreshes me after the mental strain of studying for each exam. I also feel proud of the work I've done when looking at my bookcase, just someof the little things that I find keeps motivating me.
DO NOT THROW AWAY YOUR NOTES OR HANDOUTS! I've got 11 binders so far, not counting the ones I'll make for this semester. I have purchased a bookcase from IKEA about 40 bucks on sale to place all my binders, so I can refer back to them when I get to my NCLEX exam. Organization will help you get through nursing school and your boards.
To have the spine chopped off is about 1.50, and in NYC the holes drilled would cost 0.05 per sheet, everything done in less than 3 min-- or you can punch holes yourself for free. I find it takes about 15min to punch yourself, but its all up to you. If you're lucky, you can catch staples or your local office supply store during a binder clearance. Mine had binders for 25 cents each, great condition.