If you don't have a Wal-mart near you, this site is your new best friend.
I've just been surfer there for the heck of it and the prices are defintely comparable to our big-box store friends. Decent shipping prices mean you save on gas.
Example: 100oz. Tide is 13.82 plus a $1 off coupon!
Check it out. Sign up and see if it's right for you!