comparative grocery shopping apps with my iphone

Tweet

I downloaded an app on my iphone called pricebook. Not sure how the thing works, I'm sure I'll figure it out evetually. What I'm looking for is an app that will let me compare the price of something in one store while I'm in another store. For instance, I'm in Wal mart, the milk is $3.00 and I'm wondering how much it is at Krogers five miles down the road. Is there an app for that?