In the USA, the reason for the high is two fold...

1 - This is the MAP (minimum advertised price) was set by Yamaha with pressure from the dealer network. Most of the dealers who sell Clavinova (No Advertised price allowed) want the potential profit to be in the same percentage they can get from Clavinova. They can sell it at whatever price they want. But the price of $5200 will be everywhere on the net, so they can get a local deal by giving a deeper discount.

2 - The target customer is like the 1970's/80's organ customer... 50 to 75 year old men with expendable income. Do you really think a home organ cost $4000-$5000 in 1985?!?

Always shop around and buy from someone who can help you if you need it.