Diapers can be very expensive and babies go through A LOT. The struggle to find the cheapest diapers can be a tough one, but there are places that have better deals on them.
Costco, or any other major big box type place will often have custom branded products (Kirkland for example), including diapers. They are often a lot cheaper than the other name brands. Some people already of this, some not. BUT, did you know some of these retailers will give you free shipping if you order directly from the website with enough quantity? This will really save you the hassle of burning your gas to buy diapers continually.
Also, a lot of these retailers will on occasion discount the diapers by up to 25% on top of the already good prices! When this happens stock up all at once.
Just make sure you are not buying diapers that are a size your little one is ready go grow out of!