Just speculating here, but I think the price increases are going into R&D.
The two main razor manufacturers are engaged in a cut-throat (pardon the expression) battle for market share. They always have, of course, but the battle used to be fought on the publicity front, since they all used essentially the same technologies to manufacture blades. No more.
The battle is now being fought on the technology front, with each company investing huge sums in new manufacturing processes and product design innovations. Back in the 90s, for instance, Gillette spent $1 billion on R&D to go from their 2-blade cartridges to their new 3-blade system. And, as we all know, that was only the beginning of the escalation. To understand the intricacy if the manufacturing technologies involved, take a glance at this article which deals with just one tiny cleaning step in the process
The R&D costs of developing new products are partially financed, of course, out of current sales, so I figure that the increases reflect the company’s investment in developing some new 6-blade monstrosity more than an increase in their cost of materials.
Honestly guys, wasn’t 3 blades enough?