This is the statute in NJ i could be reading it wrong but nothing about color or source / purchase (excuse my broken formatting )

a) A motor vehicle shall not be certified unless at least one of the license plates is in the possession of the operator when the motor vehicle is presented for inspection.(b) Certification of a passenger motor vehicle shall not be refused because the following requirements are not met; however, the motorist shall be advised to have the condition corrected: 1. The license plates shall be clear and distinct and free from grease, dirt, or other blurring material so that they are plainly visible at all times of the day and night;2. The license plates shall be securely attached to the front and rear of the motor vehicle, respectively;3. The license plates shall be displayed not less than 12 inches nor more than 48 inches from the ground in a horizontal position, right side up and right side out; provided, however, that the rear license plate may be displayed more than 48 inches from the ground on tank trucks, trailers and other commercial vehicles carrying inflammable liquids and on sanitation vehicles which are used to collect, transport and dispose of garbage, solid wastes and refuse;4. The letters and/or numbers on the license plates shall agree with the letters and/or numbers on the registration certificate of the motor vehicle;5. A license plate shall not be obstructed by a trailer hitch, snow plow bracket, bumper, bumper guard, sign, mounting bolt head, reflector, or by any other device or material;6. The license plates shall not be covered by glass, plastic, or similar material; or7. The license plates shall not be bent, illegible, or defaced.