Collect chairman badge, chairman badge worth how much money?

Someone once took a chairman MAO 1968 national mountains and rivers a red badge asked me the value of how much money?I couldn't answer him for a moment.Although oneself are engaged in insignia to make an industry, but collect to insignia also just a layman.Later, when I checked the badge materials, I found that the "one piece of red" badge was issued between February 1967 and October 1968, and there were dozens of kinds of them. The background color was generally red, and the main elements were chairman MAO's head, China's territory, light, red flag, sunflower, huabiao, changcheng, tian 'anmen and so on.Material is seen with aluminous qualitative much, plastic, ceramic qualitative next.On the price, aluminous qualitative small is controlled in 5 yuan, large want 100 yuan, and copper qualitative should be in 100 yuan of above.