Purchase and register launchpad for ebooks (there"s a 3week trial) Slides are what"s most important in the textbook according to prof but still refer to textbook. Chances are if you buy a used book you won"t be able to use it on launchpad. Launchpad costs roughly for ecn at campus store. Resources are scarce (limited resources), anything that can be used to produce something else (land, time, labour, capital. ) There"s only so many of us and so much land to spend on productive activities. Anytime you have to make a decision over something else. If you are thinking, i would rather be , you are referring to opportunity cost. It is all about what you have to forgo to obtain your choice. Comparing the costs and benefits of doing a little bit more an an activity vs. doing a little bit less.