At this point the (emerging) debate (in the UK and elsewhere) isn't about book prices but about treatment of tradpub authors. Consumers have advocates and allies but in many cases the people who should be watching out for authors' interests have been acting to their detriment.
The entire publishing industry has been obsessed with reader spend for five years now and has done nothing as money flows everywhere *except* to the authors, often on purpose. (When RH had their big windfall a couple years back and dished out bonuses to everybody from the CEO to the janitorial crew, the author didn't even get a mention. Reading the self-congratulatory letter it appears as if the books that generated the windfall came from the CEO and not an author.)
People are finally noticing the tiny (and declining) advances, the obscure and delayed reporting, the onerous clauses and increased demands... And above all, the low royalties.
There is nothing new in the SOCIETY OF AUTHORS statements nor in the report that triggered it; it is all well-trod ground for anybody who has been paying attention to the emergence of indie publishing. Instead of pondering whether a book is well priced, how about pondering why a publisher needs a lifetime of copyright control of an authors work, or why as much as two thirds of a book's price goes to people who neither wrote it nor sell it.
People who say they don't mind high prices because they want to encourage the author to keep writing ought to take a closer look at where their money goes because 87% of their money goes anywhere except the author and in many cases paypal-ing the author a dollar or a pound would do more for them than buying their book.
I'm reminded of the scene in Dark Knight Rises:
http://www.youtube.com/watch?v=q3CLc0IGstk
There truly is a storm coming.