The total cost of Versailles is difficult to estimate. The following response offers the reasons why it was and still is difficult to pin down, as well as the best 'guess' made by historical sources.
1. The residence was originally built by King Louis XIII in 1624.
2. It was expanded by his son King Louis XIV beginning in 1669.
3. By the reign of Louis XIV the political power shift towards absolute monarchy the King paid little attention to the cost of expanding the palace. The previous Ministers of Finance were replaced by the King Louis XIV himself, therefore he was not accountable to anyone in his his court.
4. As King Louis XIV exercised an increased control over the French government by moving his central residence from Paris to Versailles, the nobility continued to weaken and the common people were considerably alienated and disenfranchised from the King.
5. Most historians conclude that The Palace of Versailles cost in excess of One Billion U.S. dollars to construct. We must remember several rooms were really painted with gold and some of the furniture was in silver. Combine that with the marble, the fountains, the grounds themselves and the price even by todays' standards is staggering.
6. One last thought...although the dollar amount of Versailles is still only an estimation among political and economic historians, I cannot help thinking that King Louis XIV grandson Louis XVI paid the ultimate price, first for the tyranny of Absolute Monarchy second for the 'in your face' display of the Palace called Versailles.....