Many people are convinced that the cheap juice tends to make better apfelwein, actually. I wondered why that was, but just made it without going too expensive anyways.
However, I recently started buying a higher quality apple juice because it comes in the exact same 1gal jug I've bought from my LHBS... for $1 cheaper. And drinking it has reminded me of the other more expensive apple juices I've had in the past, and I think I might know why so many people swear by the cheaper stuff.
When drinking just the juice, the cheaper stuff invariably seems to have a far more noticeable acidic bite. And my guess is that the greater acidity is more conducive to a great final product.
So I'm going to use this higher quality apple juice to make several 1gal batches (might as well even ferment in the jugs they come in!), and use varying amounts of acid blend (and maybe tannin, too), and a batch with just juice, and compare/evaluate them. Even just coming up with an ideal pH would be nice info to have.