Ok. I now have a question about honing.

I see that the blue corticule stone equates to the Norton 4000
and the yellow to the 8000 or maybe 12000.

Well the norton is noticably cheaper so why should I spend the extra $$$$. What am I missing here? The 3x8 Norton combo 4k/8k goes for $75 while the Belgium Corticule Yellow (3x8) go for about $175 Blue (3x8) go for about $70.
Now I know the expression "You get what you pay for" might apply but $75 vs. $245.
Any thoughts??