Buying From A Private Party:
Many enthusiasts sell used parts on bulletin boards, auction sites, such as Ebay, or from their personal Web sites. This often requires a leap of faith on the buyer's part, as the seller will probably insist on a cashier's check or money order before sending the part. If you're comfortable with making such a transaction, be sure you know the part will fit your car. Ask the seller to describe the part in great detail, including casting numbers or other identifying marks, because these are usually "no return" transactions. Finally, keep in mind that the seller's idea of "mint condition" may be light years away from yours, so the pristine part you expect to get may be a little worse for wear.
Record Your Transaction:
Print out the order page you filled out online as a record of the transaction. If there's a problem later on, you'll have the hard copy of the order to refer to. If you feel a company has acted in bad faith, there are several online agencies that can offer assistance. The Better Business Bureau has a Web site and has taken a keen interest in online shopping problems.