If you have a Costco or Sam's Club near you, you can get a membership to those places and purchase diapers such as luvs, Huggies, Pampers diapers and many other items in bulk and save a good deal of money.
You could also check on diapers.com or other online stores and you might find Luvs baby diapers cheaper than in some stores and you might not have to pay sales tax either which could save you even more money.