Tools. Take a look at buying reconditioned, instead of new. Over the last decade, or so, I have bought many of my tools from cpoindustrialtools.com These guys sell factory reconditioned Makita products. Typically at 25-30% less that shelf prices at the big box stores. I have gotten some real interesting stuff from them. On occasion, it's sold as reconditioned, but obviously brand new. In other cases, it's is a tool with extremely light evidence of prior use, such as a slight scratch. In one case, I got a killer deal on an ultra-light circular saw that was almost perfect, but the blade guard had been replaced with a used one, with another company's ID info. engraved on it. I recently started buying similar stuff on Amazon, and scored a leaf blower that listed for $200, sells for $160, and was $104 with no tax and free delivery, as a reconditioned unit.
Material. Be aware that big box stores love to create the illusion that they are the go to place for low prices, and that this is a fantasy, in many cases. If you are doing a big project (new garage, room addition, finishing a basement, etc..... you need to get bids on the material. Draw up a professional list, and present it to Home Depot, Lowes, and your local suppliers. Be sure to tell the local guys that you are paying cash, before delivery. There are areas where my local suppliers can, and do, beat the snot out of the box stores. I can literally have a whole house trim package, Doors, baseboard, casing, closet shelving etc.... for less than half of the shelf price at my local HD. If you are doing a one and done deal, and do not need to maintain a relationship with your local, independent yards, you can also take the lowest bid you get and make HD beat it by 10%. As a builder, I needed to keep my local guys in my corner, but I have seen some guys do this with big jobs, and save stunning amounts.