A few things to remember: 
A raincheck is a promise from the store that when the item is restocked, they will sell it to you for the price on the raincheck (the original sale price).

You can only get a raincheck if a store is out of product.

You cannot get a raincheck on "While Supplies Last" or "Limited Quantities" products.

Some raincheck have time limits on when they must be used.

You can ususally only get a raincheck on an advertised item.

You can still use your coupons, as long as they haven't expired! You might even get new coupons while you are waiting, thus saving even more money!