How much is Cao Shuangdian's calligraphy worth?

No matter whose handwriting is good or not, there are valuable and worthless, expensive and relatively cheap, so you can't say it in square feet, you can only say how many pieces per square foot. Long Ge has no clear purpose, but only a reference, mainly depending on his own judgment and understanding of his paintings and calligraphy, as well as the hype in the market at that time. My own opinion, please forgive my mistake!