Moving can be a very large expense and should be handled with careful planning, even down to the very boxes that you will be using to pack your household belongings in. You can always search the local grocers and liquor stores for free boxes that they may sit out for local residents that need boxes to use for a move, but it is often best to try to locate a business that sells boxes that are designed specifically to use when packing a home up for a move.
Shopping around is always going to be the best advice to use when you are looking for moving boxes. Calling the local moving truck companies such as U-Haul, Budget, Ryder and others is a good idea as they sell moving boxes in all sizes as well as packing tape, furniture blankets and other moving supplies that will be necessary during your move. If you purchase your boxes from U-Haul and you find that you do not need all of the boxes, U-Haul will provide a refund for the unused boxes and they can be returned to any U-Haul location in the United States.
You may also want to check online for sites that cater to movers and sell moving boxes and packing supplies. Companies such as U-Line and Cheap Moving Boxes both sell moving boxes and other packing supplies at discounted rates and may be able to help save you money if you need to purchase items in bulk amounts.
If you are in a hurry and low on funding for purchasing moving boxes, you can always run to the local grocery store, Walmart or discount store to see if they have any empty boxes that you can take to pack your items in. Keep in mind that these boxes, unlike true moving boxes, will not usually be as sturdy and you will need to use strong packing tape to make sure the bottoms and sides of the boxes will not rupture during the move.