The following is aimed at those who love to buy books. However, the information included can be adapted to whatever your field of purchasing is. When buying a book on ebay, keep in mind what that book might cost outside of Ebay. Do a check on various websites such as Addall.com and allbookstores.com not to mention Alibris, Abebooks and Amazon. Check sites that also sell new books such as Barnes & Noble. You would be surprised at what you might find. Check the description and picture as to the quality of the book. Compare that description with the price and quality described at the other sites. Check feedback...If there are negative, check what type....If it is just length of time it takes to arrive, a lot of times that is something the seller is unable to control. Check that emails are returned, packaging is good and service is reasonably well done. Check for shipping costs. Many sellers include shipping costs that are excessive in my estimation. Something that only costs $4 US dollars for shipping and packaging stuff is sometimes double that. These excessive costs could be an attempt to get the actual book price the seller wants irregardless of what the starting bid or "Buy It Now" price is. Do not be afraid of International shopping. Some of my best buys have been outside the U.S. Use the XE.com website to translate the currency from one type to another. A quick email to the seller giving (for U.S.) State, zip code, and Country usually brings a courteous email stating approximately what the charges would be. When bidding on a book, figure how much total you want to spend, then subtract the shipping charges from that amount. Use that final amount as your maximum bid. One other item--when bidding on a multi-book auction, decide how many of those books you actually want. Then divide the number of those books into the combination of shipping and, if Buy It Now, purchase price to decide if the cost PER BOOK of those specific books is within the amount you wish to spend per wanted book. If it is an auction, again consider shipping charges with your maximum bid divided by the number of those specific books in the auction. Thus all the other books become bonus since you didn't necessarily want them while those you did will have been bought according to the value you decide each is worth. This also holds true when it is a single book auction---the cost of shipping combined with the purchase price is the amount you will pay for a book. If you are trying to purchase a number of books, take a moment to check a seller's stores. A lot of times you can buy multiple books on auction via one seller and thus save on shipping charges. Don't hesitate to email the seller asking what those charges would be if you bought "so many" (give the number of books) at one time. I have saved many dollars in shipping by doing this. Good Hunting!