They say the difference in price is like comparing a Toyota with a BMW
What is a surprise, is the number of colours that result.
Other metal compounds can have particular colours, such as the red of lead or iron oxide (rust), the blue of Copper nitrate, and while silver nitrate has been used in photography, This is the first time colours have been drawn from Gold and silver in this way. One of the reasons Gold is so expensive, apart from it's history, and the futures market, is because it has so many applications.