The White Palace in Ankara has 1.6m square feet of floorspace, and features thousands of trees imported from Italy at a cost of up to $10,000 each; the taxpayer-footed electricity bill from the palace will run $313K/month.
Erdogan was the architect of the violent crackdown on the Occupy Gezi protests, which filled the streets with Turks who were fed up with official corruption. He also created the nation's system of extreme Internet censorship, just as secret recordings of he and his family and cronies engaging in bribery and gross corruption to the tune of ₺100 billion began to surface.
Nevertheless, he was re-elected in August.
Speaking to the BBC, the Ankara Architecture Chamber said the latest price hike was in part due to thousands of trees which have been imported from Italy to be planted in the palace grounds.
The price of the trees was not included in the original bill, and each tree costs between £2,400 ($3,750) and £6,400 ($10,000), the chamber said.
The BBC's correspondent in Turkey Mark Lowen said the new palace is now seen as an example of the extravagance and omnipotent style of Mr Erdogan, whose AK Party has dominated Turkish politics for more than a decade.
The project has also been lambasted by the political opposition, which pointed out that the monthly electricity bill alone - likely to be footed by the taxpayer - will reach £200,000 ($313,000).
The president has called the palace a "show of the country's prestige".