The Nikkor 4mm f/2.8 lens was first developed in 1999 and still today, they sell in the UK for circa £1300. Whilst the lens suffers from complex distortion, it has always performed well on every Nikon I’ve owned from the D80, D2x, D300, D300s, D700 and D3.
The Nikon 14mm f/2.8 AF-D is a huge improvement over the manual focus 15mm f/3.5 AI-s and other older ultra-ultrawide lenses. This fixed 14mm is smaller and weighs exactly 2/3 what the huge new 14-24mm f/2.8 zoom (introduced in 2007) does. This means this fixed 14mm weighs 333g (12 oz.) less than the zoom!