An ebook being cheaper isn't a big deal for me, since my view is the price more to do with the content than the format. For other people it does seem to be more significant though. Maybe it should be the price of the physical book less the costs of printing/binding/etc. such that you get the same amount of money in the pocket at the end? (I don't know if that's how it works, having never published a book!)

PDF is good for PC viewing and will work on pretty much everything, though EPUB and Kindle formats will make things better on e-readers and phones/tablets since they support re-flowable content, but I guess would probably require more work on your part to support.