Mary beat me to it. Many home brew supply shops sell juice for making wine. I have seen it both as regular juice and as concentrated. Unfortunately, I will assume that most of it has been heat processed at some point so that might affect the flavor and destroy some of the nuances. I am only assuming as I have not attempted wine before (though I have brewed many a batch of beer). So start by checking shops and then search the internet, I know there are a lot of resources out there.