It's always been my experience that the store brand is cheaper than the name brand even with coupon.
Nope. Sometimes this is true, but my local store doubles coupons with a face value under $1 every day, so taking that into account, here's a real-life example:
Store-brand sour cream: $1.19
Daisy-brand sour cream: Regular price: $2.45
BUT, it's on sale this week for 2.19, and I have a 75 cents-off coupon, which doubles to $1.50. So I net the brand-name product for $0.69, about 43% off the retail price for the store brand.
Even without the base price on temporary reduction, I might do even better with a coupon on a name brand if it's one of the every-six-weeks special coupon weeks. They alternate between "super double coupons" (double anything under $2) and triple coupons ($0.50 becomes $1.50). So if it's triple-coupon week, even if Daisy sour cream isn't on sale, I still get it for $0.20. If it's on sale AND I have a good coupon, I might get it free.
Harris Teeter's store-brand products are cheaper than name-brands, but usually the margin isn't so large that a doubled coupon can't span it. Kroger, OTOH, has dirt-ass-cheap prices on their store brand, and since they don't double coupons except during select weeks, you'll usually do better on store brands there. But the nearest Kroger is a 15-minute drive, and I can walk to Harris Teeter, so guess where I end up most of the time?