this semester, i bought 2 from half.com for $50 each (saving $25 each).
but...
both sellers have disappeared, leaving me with no books for this semester. it takes 30 days to file a claim, so i don't get my money back for a month. no big deal, but now they're selling for $75 (which is also the bookstore price), and if i buy another one, the seller might turn up & then i'll have 2 of the same book.

so i guess my experience with online book buying hasn't been that great.

Amazon.com, nothing but good luck. I even MAKE money occasionally (sp?) sellling them back...