For those who are unsure of what shoe type they are, have a look at this link.
It takes five to 10 minutes to complete, although no substitute for a gait analysis test at a specialist shop, it gives you a pretty good idea when deciding upon a new pair of trainers.
Yeah they are expensive, it is a Mizuno site so its in their interest to promote the new range. Just use the equivalent shoe type available from your prefered brand.