I once heard an expert analyze the prices of calligraphy and painting in this way. I hope it will be helpful to you.
The prices of the same or different calligraphy and paintings are different in the eyes of different people, but no matter who has good or bad calligraphy and painting, some are valuable and some are not valuable, some are expensive and some are relatively cheap. It's a little bit, so we can't generally use square feet to talk about it. We can only say how much a certain piece costs per square foot. Runge doesn't have any accuracy, it's just a reference. It mainly depends on his own judgment and understanding of his calligraphy and painting, as well as the market hype at the time. A calligraphy and painting will have different prices in different places, at different times, and in the hands of different auctioneers. Therefore, it is difficult to judge, let alone an absolute price; besides, any personal evaluation is only one-sided and personal point of view. Featured, famous, or wanted by someone special, these may make the price higher. But if the price of calligraphy and painting is high just because someone has a position now, or it is purely speculation; then when he quits, or there is no one to speculate, the price will soon drop, and it will even become worthless. The same goes for any other piece of art. As long as it's in good condition, it has collection value. What is particularly pointed out here is that Runge is an unreliable reference. It mainly depends on the market and your own understanding of the work, as I said above. In addition, you can check out relevant art websites such as Artron Gallery. Well, having said so much, let’s use it as a reference.