Extreme Couponing on TLC

I only managed to watch Extreme Couponing on TLC once. I was amazed at how coupons can reduced the total price of the items that you purchased from hundreds of dollar to just a few cents. I wonder whether online shopping coupon codes can do the same. I know where to get free shipping codes and a few other coupon codes but those coupon does not reduced the price until more than 50%. No chance of learning how those shoppers do it coz hubby has disconnected the Astro at home. :(