Based on my experience in products and how much you can sell them talking about factors the color is valued in tech (more in iPhone products)some colors do not have a wide market, some group of people may prefer the white one and the green one is left behind when choosing one based on that the market adjust the price and make the white one more expensive because probably they have a long list of green ones and less units in White so they are saying to the people “Hey buy one in green better we have a better price for it”. Its all about marketing