MILES to GO || before I sleep

So I'm trying to find my textbooks before classes really get underway and I'm left behind. I'm checking all the usual haunts-- Half.com, eBay, Amazon, my own Matador Bookstore, etc. This time I've even added AbeBooks and the publisher's own stores to my list. I can also check out TextbookX and a few other places, but generally what I'm finding is that all my textbooks are ridiculously expensive. This is just one of those semesters, I guess.

I can buy direct from the publisher-- a digital version of my Biology book that's either online or downloadable.

PROS
* Cheapest version available, even when taking into account severely used copies, copies without the Physiology CD, and International Editions
* No need to schlep around a heavy book
* Easy to copy-paste info into my digital notes, easy to highlight sections (assuming it's a PDF or something)

CONS
* Can't be sold back anywhere, anywhen
* Is probably a huge amount of MB or even GB, considering it's a 1024 page book in digital format
* Requires computer (if not external HD) to be present, and likely another program to be in use when reading the text-- which means less memory for my digital notetaking, online research, or whatnot

So... physical copy or digital? What would you do?

I suppose in the meantime, I should look for my other textbooks.