Damn, those things are expensive. Most schools give students access to their gym (oftentimes included in tuition and activities fees, without your permission) so just use the gym. Most people can't study while running anyway, so I doubt that's a good excuse for getting one of your own at home. Thirty minutes every couple of days is not that big a deal. Most people spend more than that every day eating crap or checking myspace or facebook. Assuming you have access to a nearby gym, do that. Plus it's more motivating because you are there to specifically workout (or pick up members of the opposite sex, but let's assume exercise is the main goal). Home can be distracting and you may find yourself taking unneeded breaks and not exercising very much at all.