Despite the fact that I try to run to the stores on Sunday and get the great deals, sometime I do miss out. If this happens to you, don't worry - all hope is not lost. Here is a phrase every extreme couponer needs to learn: "Can I have a raincheck for that item?"
Rainchecks are WONDERFUL! Most stores offer them on most sale items, but not all. If a sale item is out of stock you can get a raincheck that allows you to get the item for the sale price when it comes back in stock, after the sale has ended. This rocks because within a week of the sale ending, the shelves are usually fully restocked.
The biggest risk is that your coupons may expire before the item comes back in stock. Even if this happens, all hope is still not lost! Coupons are fairly cyclical, so hang on to that raincheck and often a new coupon for that item may be released within a short time.
TIP: Don't wait until the last day of the sale to get your raincheck. The very first time you go to a store and an item is sold out, get a raincheck. Don't believe them when they say they are getting another shipment on Tuesday. Often an item will never come back in stock during the week, or if it does, your extreme couponing comrads may grab it up before you can get there. Get the raincheck right away. If you go later in the week and the item is in stock you can buy it, but save that raincheck for a future awesome sale/coupon matchup. Sometimes you can even coordinate it with a store reward too!