When I re-bought the first three volumes of the Song of Ice and Fire series (I misplaced my copies) I specifically compared the e-book prices with the mass-market paperbacks. They were exactly the same price, so I went with the mass-market versions, not because I have a particular affinity for physical books but because, as an employee of a certain large bookstore chain, I get a discount on physical books that I don't get on e-books. If publishers really wanted to save money on printing costs they'd price their e-books more reasonably.
That said, they recently reissued the Harry Potter series in new trade paperback editions that are absolutely smurfing gorgeous and I'm having a hard time resisting the temptation to pay the $75 or whatever I'd have to pay to get the boxed set.