What is the price of wine in ancient times?

The price of wine in ancient times is an interesting topic with many different opinions. According to "Xuezhai Zhanyou", Emperor Zhenzong of Song Dynasty asked the prime minister Ding Wei: "How much was the price of wine in the Tang Dynasty?" Ding Wei said, "Thirty cents per liter." Emperor Zhenzong asked what the basis was. Ding Wei quoted Du Fu's poem, "Come and drink a bucket of wine with us, and you will get 300 bronze coins" as proof. Song Zhenzong was very happy and thought that Ding Wei was very learned. However, Li Taibai's poem "A bucket of wine in a golden bottle is worth ten thousand dollars. One is a bucket of 300 dollars, the other is a bucket of 10,000 dollars. Li and Du were contemporaries, but why was there such a difference in the price of wine? Some people jokingly said that Taibai was talking about "fine wine", while Du was too poor. Maybe when the scribbles, hunger is not choose to drink, is in the village store thatched cottage drunken drink also! In fact, the phrase "a bucket of ten thousand" is an allusion. In the poems of Bai Juyi and Liu Yuxi, there is also the line "I'll put 10,000 into a bucket". According to the "Biography of the Immortals", when Emperor Huan of Han Dynasty (147-167 AD), Wang Yuan passed through the Wu Xu Gate and dealt in wine with Yuhang Buxu for a thousand coins, and got five buckets of wine, which amounted to 200 coins for each bucket of wine. Cao Pi, the Emperor of Wei, discusses in his Canonical Discourses that at the end of the reign of Emperor Lingdi of Han Dynasty (188 A.D.), the hundred priests indulged in wine, which was worth 1,000 wen per bucket. Cao Zhi and Cao Pi were brothers, and Cao Zhi's poem "one thousand dou" is an exaggeration by the poet. Li Bai and Bai Juyi's poems were also like this. Therefore, the price of wine throughout the ages was about 1,000 wen per bucket at the most expensive time, and about 40 wen per bucket at the cheapest time. As for the price of wine in Du Fu's poem, a bucket of 300 cents, is it consistent with historical facts? The book of Tang, "food and goods," recorded that Emperor Dezong Jianzhong three years (A.D. 782), prohibited the people deal in wine, set up a market wine, dendrobium value of 3,000. That is, each bucket of three hundred dollars. But this is already 12 years after the death of Du Fu. However, Yang Songjie "talk about the Yabu" in the account that the Northern Qi Lu Sidao once said, Chang'an wine cheap, bucket price of three hundred. So it seems that, whether it is realistic or use of canonical, Du poetry "bucket wine 300 money", are based on, rather than make up their own minds.