Why is Mizuno golf equipment so expensive?
To the uninitiated, Mizuno seems pricey.
To those who appreciate forged irons, Mizuno is the "entry-level" of Japanese-forged clubs.
To make an educated decision what makes a difference to you takes an understanding of forged versus cast irons and a belief that there's a difference for you.
After forged versus cast, read up on muscle-back versus cavity-back. That'll really help narrow down which club-heads appeal to you.
Hit 'em well!