I am a big fan of smaller sensor "mirror-free" systems, be they 4/3" or 1", but am puzzled by the pursuit of lenses with very low minimum f-stops like f/1.2 primes and constant f/2.8 or faster zooms: it is a bit like a small, agile basketball player aspiring to play center. This lens illustrates the difficulties: it seems that the challenges of the f/1.2 design and/or the relatively low expected sales volume put it at a price disadvantage compared to lenses that give comparable FOV, DOF control, and low light handling in larger formats ($900 in the USA). In this case, the peers would be about 45/1.6 in 4/3" format, 56/2.1 in DX, 85/3.2 in 35mm format, and lenses offering roughly those specs are available at lower prices in each case.
On optical problem is that whereas f/1.2 in 35mm format has very shallow DOF wide open so that a bit of softness towards the edge of the frame is usually unnoticable, this lens has almost three times as much DOF wode open, so the demand for edge-to-edge sharpness even when wide-open is greater. I am not saying that this is not possible, but it might have added design challenges that contribute to its relatively high price.
On the other hand, I believe that this is the first Nikon One lens with a manual focusing ring, so that is progress.
P.S. to Paulo: the Olympus 45mm, f/1.8 at about US$350 is a closer match in 4/3" format, though with a slightly smaller effective aperture size. The 43/1.2 pre-announced in February by Panasonic will be another option ... but I suspect that it will also come at a price that makes me skeptical.