If your storage needs are short-term, the shed may not be a good idea. Most people with a shed tend to fill them with clutter and then ignore it. With longer storage needs, a shed gives you a one-time cost that would indeed be lower than paying for years at a commercial storage unit. Be sure to factor in the cost of assembling the shed if you are unable to do that part yourself. Also, consider how much of your yard space you are giving up for the shed and will it need repainting and repairs over the years. Ultimately, reducing the amount of stuff you are holding onto is the best way to go. Keep in mind that a shed might be humid and hot or get invaded by rodents and insects, so do not expect to store things like boxes of books or your family photos or things like quilts and clothing. Those need to be in climate-controlled storage such as inside your home or in commercial storage space.