>>1687997(Assuming that this is medieval and paper currency doesn’t exist)
In the original Italian gold ducats (about 3.5 grams each) that is 70.9 metric tons of gold. 70.9 tons is almost half of the Earths total gold supply.
Although Ducats in other denominations have been minted by several countries (highest I know of are two 100 Ducat coins) they increase in size and weight in proportion to the denomination, making the elf even more expensive.
At modern gold prices, that much gold is about 3 trillion USD. No single person (taking inflation into account) has ever had that much money. At this price, assuming the buyer will live another 60 years, and that he will spend every second of that time having sex with her, then each hour of sex will cost 5704 USD.
If we were to assume that a “Docat” is roughly equivalent to the modern Yen, then it would take 280 kilograms of 500¥ coins to buy her.
If we assume that a “Docat” is equivalent to the least valued modern currency (Persian Rial) and she was purchased with the most valued modern coin in circulation (500¥) it would take 160 coins weighing in at a little over 1 kilogram.
TL;DR: Really fucking expensive