As mentioned, the cutting plotters are generally large but they come at different prices. Before you head to the store you should take the measurements of your space and buy a unit that will adequately fit there. You should leave enough space in front and behind the plotter to allow you to walk freely in the room. The extra space also allows the large paper to lay undisturbed when the other portions are being cut.
You should also consider where you are buying your machine from. As rule of thumb ensure that you buy from a reputable cutting plotters store. This calls for you to research and go with a company with the best reviews.