When you are packing for a move there is one thing you know you will need plenty of... moving boxes. During the packing process you will literally pack up all of your belongings into moving boxes.
Using old or dirty moving boxes can actually do more harm than the money you save. One common place people get used boxes from are grocery stores. This source is one you defiantly want to pass on because of what was in them prior to you getting them; that being food. Food can leave behind residue or bacteria. Food particle can begin to mold and then get whatever you put into the box contaminated with mold, possibly making you sick after unpacking. You should be weary of other sources as well as you do now know where the boxes have been or what was in it prior. A more trust worthy source for boxes are a moving company as they know which ones to not reuse and which ones are ok. It is always a good idea to talk to you local movers about moving boxes. See if you can get a deal on them with your move or see what your options are.