From my own observations ... When these bikes were new on the showroom floor certain colors were clearly more popular in sales. Going fast forward 40+ years, the used bike market still commands those same original popular colors. I bought my first K1 back in 1971, I absolutely had to have the desirable candy gold, which I was lucky to get. Many of the less popular original colors ended up as custom paint jobs making them even more rare now, but not necessarily more valuable.