textbooksHi, my name is Susana. And I have found that you have got to reasearch books, before you buy them.
1. Always consider whether the book is new or used. Just because it is used , doesn't mean it's no good. There are many use books out there that are just like new.
2. Know your isbn number. This is a great help. You can research the currnet prices on many websites and even see if it's on ebay.
3. If you find it on ebay look for submit your best offer. This is a great way to negotiate a reasonable price. 
)