Of course they are worth that much! At least they are to the guy who has bought them - just before he handed the money over.
Afterwards? Well, they are very nice chisels, no doubt. Well balanced, even beautifully balanced. A nice fine bevel (even if I did cut myself once, gripping it too hard as I worked a dovetail) that few modern chisels have.
Wonderfully flat and well shaped. They really only take a couple of minutes per, to make them into the perfect woodworking chisel.
The steel? I really don't know but to my mind there is little to choose between the LN chisels and other good ones I have (like pre-war cast steel chisels) in terms of sharpening and edge holding. I have done no scientific tests so I am simply reporting impressions gained through normal usage in a variety of hardwoods.
If you were keen, you could get equivalent chisels by buying really good second hand ones, making new handles and grinding them carefully to a desired shape.
I dunno about anyone else but my time is worth more than the differential cost.