I'm not price sensitive at all, but I have a few factors going into it:
-Some of what I read is old/classic and so is free.
-I don't read a lot throughout the year - just getting to 50 in a year is a challenge for me.
-I'm pretty picky about what I read, so when I want to read something, I want to read it no matter the price (well, unless it were really exorbitant). If it's too too much in ebook, I'd probably try to get a pbook cheap off ebay or something.
-For the most part, I don't buy books until I'm ready to read them. I don't have to worry about impulse buying (anything I'm really interested in I just add to a list), so I guess it's easier to spend more if I have to when I'm just buying the one book I want to read at that moment.
When I am buying though, I do love when I can use discounts, coupons and codes to save money off whatever the price is!