It's the big one I'm looking at as well.
How much?
*caution - vast speculation*
If you consider they used their largest oval base (170/105mm - a little less that 7 inches), that tells you more or less how long it is as the ship appears to be about the same length as the base. It appears to be as high as it is long, so 170mm (7 inches) tall. That would make the ship structure somewhere around 170x170mm or 7x7 inches.
As it is almost certainly the "Command" ship, and based on other somewhat 'close' miniatures of that size, such as Alarielle the Everqueen Sylvaneth leader and the Everchosen model of Archaon, it's probably going to priced somewhere between 80 and 100 British pounds, 105 to 130 Euros or 130 to 165 Dollars.
So... not cheap... by a long shot.