Well, the 250 ninja is a great bike. i have one of the older models (a 2000 and my ex has a 1999). They are fun little bikes. Will they win you any competitions for speed-no. But they will get about 65mpg combined (city and highway) and are a blast on mountain roads. They are just lightweight, fun "flickable" bikes.
Yes I agree the price is high for the redesigned model. But hey someone has to pay for all that retooling.
As for emulating them, well years ago Honda imported for a year or two the 250 Interceptor. I have only seen one briefly. It was an early 80's model I believe. I am not sure if it was water cooled or not. They never sold well here in the states, so Honda stopped importing them. I believe they are still available elsewhere thruout the world.
I am sure that if the redesigned 250 ninja sells well, and all indications are that it is a very hot commodity, that the other 3 manufactors will look to import something simular soon.
Ninja 250-pluses-light, agile, very manueverable. Proven reliable powerplant-even it was slightly redesigned. It was detuned slightly to give the new ninja more bottom and mid range torqe, basically the powerplant and electronics are the same, it is just the frame and body plastics, as well as the wheels that were redesigned.