To determine how much your trailer is worth, visit a vehicle guide site, such as the National Automobile Dealers Association, or NADA. Enter your ZIP code, the make and model of the trailer, and the year it was manufactured. Enter any requested information, and find out the trailer's estimated value.
As long as your trailer was manufactured after 1970, find the value on a guide site. Indicate the mileage of the trailer if it has a gas engine, as well. Once you enter all the needed information, the guide site provides you with several suggested values. The highest value is for a vehicle that is in great condition and newer, while the lowest value is for a trailer with mechanical or cosmetic problems.