Just to follow up on Semaphore's comment. The price of silk was highly variable during Roman times and it was considered the ultimate luxury item.
In both the Rhodian maritime laws and in accounts of the reign of Aurelian (270-275 AD) it is implied that silk was worth its weight in gold. So, for example, the silk in a garment weighing one pound might be 14 troy ounces of gold or about $16,000 in modern dollars. Note that 1 pound of gold = 12,000 denarii.
By the reign of Ammianus Marcelinus (c. 380) silk was said to be much more affordable and the upper middle class could wear it.