This is from the BMV's website on collectors plates. more info here
In an effort to ensure that all vehicles registered as collector vehicles are truly collectible, the Bureau of Motor Vehicles references the National Automobile Dealers Association, Classic, Collectible, and Special Interest Car Appraisal Guide or the 4th Edition Standard Catalog of American Cars 1946-1975 (Krause Publications) or The Complete Book of Collectible Cars 1930-1990 (Consumer Guide) to determine vehicles that are true collector vehicles. Although we recognize that a vehicle may be unique because of time, energy and investment expended by the owner, these publications are used in determining eligibility for collector’s license plates. Due to a administrative ruling, vehicle models not listed in the above publications may be considered collector vehicles if the applicant obtains documentation from the manufacturer that the vehicle was in limited production, is in demand as a collectible vehicle at the time of application or a sizable investment can be proven.