How would you like to buy today's best-selling books for 30 percent or 40 percent off the suggested retail price? You can on the Internet as long as you don't mind buying a "slightly used" copy. There's hardly a wait because used copies of best-sellers are often available just a few days after their release.

Big online retailer Amazon (www.amazon.com) lists used books alongside new ones. On a book's product page, there's usually a link for used copies. It lists the number of available copies and a starting price.

Click the link to see what's available. Sellers list the price and condition, along with special notes. You buy used books the same way you buy new ones. Amazon processes the payments and the seller ships the book directly to you.

If you're skeptical about a seller, review the rating and comments left by other buyers.

Amazon isn't the only game in town.

Alibris (www.alibris.com) specializes in used and new books. It connects independent booksellers to buyers.

Again, the book's condition is listed along with other notes. The selection is impressive.

Abebooks (www.abebooks .com) and Barnes and Noble (www.barnesandnoble.com) are similar to Alibris. Sellers are independent booksellers. None of these sites takes possession of the books. They simply facilitate the transactions.

Powell's Books (www .powells.com) also has a separate used section. It's like a traditional book store. Copies are shipped directly from the store.

You also can try eBay (www.ebay.com) if you feel like bidding.

Or eBay's subsidiary, Half.com (www.half .com), lists items at a pre-determined price. Books are grouped by condition, and sellers can leave special notes for buyers.

Most people who buy from these sites are looking to buy recent releases at deep discounts, but you also can find old classics. Avid collectors peruse these sites looking for rare books.

The rare ones are easy to spot because they have hefty price tags.

If you're a student or know one, many of these sites sell used textbooks, which can add up to considerable savings, too.

You also might want to sell your slightly used books. Amazon, Half.com and eBay make it easy. Commissions are low, so you'll likely make more than at your local used bookstore.

Amazon has a "Sell Yours Here" link on product pages. Click the link and set your price. Amazon charges 99 cents, plus 15 percent of the sales price and a low closing fee (usually less than $1). You get a credit to cover shipping. You pay when your book sells.

Half.com takes a percentage of the selling price. It varies based on the price range. For items under $50, it's 15 percent. Half.com reimburses you for shipping.

Ebay charges a listing fee and a percentage of the sale. Fees are tiered; consult eBay's fees page for details.

Contact Kim Komando at www.komando.com/contact .asp.