Home Depot (aka: Big Orange) matches prices. Lowe's offers a 5% discount when you use their store credit card. When shopping at Home Depot, if you ask for the "Lowe's 5% credit discount", they will extend that to you... at least here in California, and most specifically at the stores near me.
You often have to show them your Lowe's card and the transaction has to be on your Home Depot card, but using that card — if you can pay off the balance each month — has the additional great advantage of making returns super easy. I've never had a hassle at returns even without receipts when using the card. In fact, I rarely save receipts because of it... at Lowe's, too.
Additionally, there are often other savings or services that store cards can offer... from discounts to delivery services. Having 100 sheets of drywall show up at your house for a minimal charge is totally worth it.
Go save some cash (and backaches)!