You can go online to purchase one item at the 50% off, even if it is on sale....they allow it online, but not in the store.
Just place it in your cart and use your 50% off coupon code, it makes it 50% off the original price. Of course, you cannot use the free shipping code, since they only allow one code. So it is best to shop the 50% off sale, then use your shipping code.
Confusing, isn't it?