I’ve never bought a new car, always used. Evaluating a car’s worth is important when buying second hand. You can’t always trust the seller or car-valuators on the web and in papers. Sometimes you have to trust your gut and what the vehicle is really worth to you.
About.com have put together another great collection of articles to help buyers in the used car market.
Trade-in – The value a dealership will give you when you trade-in, or give, the used car to the dealer in exchange for cash or a down payment on another vehicle. A trade-in value is typically 20% lower than private party values.
Private Party – The value a private individual can expect when selling to another private individual. Many consider private party values a baseline.
Retail – The value a dealership or used car lot will assign to the vehicle. Used cars sold at “retail value” will often have been reconditioned, carry a warranty, or both. Their prices may be up to 20% higher than private party values.
How to Value a Used Car – [About.com]