How much should a nuke plant cost?

The new British government announced that it will be reviewing (read delaying) a decision to build a nuclear power plant financed by the Chinese to be located at Hinkley Point, England.  The strangest part of the brief article in the Wall St Journal was the price.  The plant is estimated to cost $23 billion to build.  Wow.  The going price for brand new nuclear plant is "only" $5 or $6 billion dollars for a 1 Gigawatt plant.   $23 billion sounds like a rip off to me. 
   Another odd detail about this deal, the Brits promised to pay double the going electric rate for juice from this Chinese financed plant.  Does this sound like crony capitalism? 
   You have to wonder why the Chinese are dickering to spend (invest?) so much money in the utility electric power business, which is not noted for high returns.  And to spend all that money in England, where the power helps the British economy rather than the Chinese economy. 
  Anyhow I can see why the new British government is "reviewing" this high price project.