Just for interest, here are the current prices on Amazon UK for the top 10 bestselling hardback fiction books (according to the Times weekly bestseller lists)
Code:
HB Kindle % Difference Title
6.00 10.99 83 The Faithless/Marina Cole
6.00 8.99 50 Red Mist/Patricia Cornwell
8.99 5.99 -33 Snuff/Terry Pratchett
8.55 6.64 -22 Death Comes to Pemberley/PD James
8.20 9.99 22 11.22.63/Stephen King
7.00 10.99 57 The Litigators/John Grisham
8.30 9.99 20 The House of Silk/Anthony Horowitz
6.49 5.59 -14 The Sense of an Ending/Julian Barnes
9.41 9.99 6 The Thread/Victora Hislop
8.49 4.99 -41 The Time of my Life/Cecelia Ahern
77.43 84.15 9 TOTAL
As you can see, 6 of the 10 are more expensive in kindle format. (Prices for kobo books are either the same as kindle or slightly more expensive - the total for all 10 from kobo is 87.07.)