You can often get boxes straight from the moving company you hire. Alternatively, large hardware stores often carry a good selection of moving supplies. Keep in mind, the size of your vehicle when picking up your boxes. Many large and medium boxes will not fit in two-door or small, four-door vehicles without having to be folded, which can damage the structural integrity of the box. Make sure to ask about the return policy for boxes in case you buy more than you need. TWO MEN AND A TRUCK®, for example, will purchase back any unused boxes whereas other companies may not.
If you are reusing old boxes or getting boxes from a retail or grocery store, check to make sure the boxes are clean, free of bugs, and do not have water damage, mold, or other structural damage that could cause the box to buckle during the move. While you can save money using free or old boxes, you do run the risk that they could cause damage to your items during the move.