Find discontinued plastic model kits at hobbylinc.com and oldmodelkits.com. Revell, Pegasus, and Maintrack all carry models that have been discontinued or were produced in limited number. Oldmodelkits.com carries models that are decades old, rare, and in good condition.
Collectors of plastic model kits should look for top brands such as Revell, Aurora, Monogram, Hawk, and Lindberg. There are many factors that include the value of a plastic model kit. These include the condition of the box, whether or not the pieces are partially assembled, whether the kit includes all of the original pieces, and the condition of the pieces themselves.
To protect the value of the kits, vendors should take special care when shipping their packages. It is important to use a heavy corrugated cardboard box that is new or used in excellent condition. Minimize empty box space with newspaper or packing peanuts to avoid the kits shifting in transit. All of the box seams need to be carefully taped shut so if a part of the model comes loose, it will remain in the box.
Craig Kodera provides more tips for collecting plastic model kits in his book, "Collecting Vintage Plastic Model Airplane Kits". He provides an extensive list of top brands, guidance for determining the value of a model, and ideas on where to find vintage or discontinued kits. Collectors should look for plastic model kits at garage sales and flea markets, as well as by networking with fellow collectors.