It appears to use a Phase Fresnel element to help reduce the size of the lens:
http://www.nikon.com/news/2015/0106_lens_02.htm
http://www.nikonusa.com/en/Nikon-Pro...web-0115-300mm
http://www.dpreview.com/articles/799...-5-5-6-ed-zoom
It will cost around $2000,which equates to around £1300 excluding VAT(remember exchange rates have crashed too).