I forget where you live but I think it might differ from region to region. I know here in GA a lot of people use Southern savers. I think it is www.southernsavers.com
i think that is what you are looking for...atleast that is how i do it. i get the ad-see what i want and then look it up on afc's database. i know there are pay sites that you just input your store name and it has all the match ups, but i don't use anything like that.