I might still have a few of those pbooks with the cigarette ads on my shelf
I didn't vote because there was no "It depends" choice. I would not buy a book with ads that is $1 cheaper, probably would buy one that is $5 less, and would be very likely to buy one for $10 less. This is assuming that I wanted that particular book (as opposed to browing and saying "this looks interesting...". For that I go to the free sites such as MR.)