From the FederalTradeCommission
www.ftc.gov
Internet Auctions: A Guide for Buyers and Sellers
Know Your Legal Obligations
Under federal law, you're required to advertise your product or service and the terms of the sale honestly and accurately. You can't place "shill" bids on your item to boost the price or offer false testimonials about yourself in the comment section of Internet auction sites.
You're prohibited from auctioning illegal goods. While many auction sites monitor their sites to ensure that illegal items are not being offered, the responsibility for ensuring that a sale is legal rests with the seller and buyer. Some auction sites post a list of prohibited items as a guide.
You are required to ship merchandise within the time frame specified during the auction, or, if a time frame is not specified, within 30 days. If you can't meet the shipping commitment, you must give the buyer an opportunity to cancel the order for a full refund or agree to the new shipping date. To learn more about your responsibilities when shipping products, see A Business Guide to the Federal Trade Commission's Mail or Telephone Order Merchandise Rule.