As we all know text books are very, very, very, (you get the picture) expensive and the bad thing about it is that no matter how good the condition of the book is, when you try to sell it back you don't get anything considerable for it. Here is what I did. I needed the general chemistry book but the one that was recommended was the 4th edition. The book is priced at over $100 and I don't even think that I should be doing chemistry as an ECE major. So I looked at the price of used copies on Amazon and it was just about 30% less. Eventually what I did was just buy a used copy of the third edition for $8. I know that the most recent edition has the most updated info (and less errors) but I think that the content is more or less the same. I think I will do this for all textbooks. Is this a good idea? Clearly I have already saved atleast $100.