Zheng Geping, a native of Lan County, Shanxi, is a national second-level artist, a member of the Regular Script Committee of the Chinese Calligraphers Association, and the vice chairman of the Ningxia Calligraphers Association. It is rare to see his works on the market. In the past few years, there were two calligraphy works of his at the Ningxia Jiapeng Auction Company's auction. They were estimated to be 500-1,000 yuan/square foot, but neither of them sold.
Your collection is 4 feet square, totaling 8 square feet. If you estimate it at 500 yuan/square foot, it should be about 4,000 yuan.