raonx and spry, if you don't want to buy the book, try your luck at local library (or school library if you are student). I got OG and some Baron gmat books. OG is 9th edition, I guess should be ok.
I bought used one from www.half.ebay.com for $20.00 plus $3.00 media mail. But unfortunately I just checked this website, OG 10th edition has been out of stock. You may try www.amazon.com market place for used one or www.testmagic.com for brand new one(January,2002) for $29.95.
Please pay attention if you buy used one which has to be no any pen marks on it, usually the seller will tell you or you may ask seller about it.
www.bn.com--barns & noble bookstore sells the books comparatively cheap.
Good Luck!