We really don't know how much Apple charges for their hardware because they bundle their software with it, and they don't tell us how much the software costs either.

If we assume Windows and OS X took similar developer efforts, the smaller market for OS X means it is going to cost a lot more than Windows in order to recoup the costs of development. That is simple economics. Looking to iOS, it has a much larger market and Apple's mobile devices are quite competitive price wise, which supports the software cost factor.

You might find a higher sticker price on a Mac, but it is a pretty safe assumption that the added cost is to get you into OS X. Which just so happens to be the only reason why you would consider purchasing a Mac in the first place.