In addition to the labor and materials used to make wine, the reputation of the vineyard where the grapes originate plays a role in determining the price of the finished wine.
Conclusion (therefore)
An expensive wine is not always a good wine.
Evidence
The reputation of the vineyard where the grapes originate plays a role in determining the price of a finished wine.
Evaluate
To prove that "X is not always Y", we have to establish that sometimes X occurs even though Y doesn't.
So in this case, the author is trying to prove that sometimes you have an expensive wine, but it's not a good wine.
Does he supply an example of an expensive wine that isn't a good wine? No, his evidence is really bad and loose.
He just talks about three things that could make a wine more expensive: - the labor used to make the wine - the materials used to make the wine - the reputation of the vineyard
He must be assuming that it's possible to have an expensive wine (through some combo of how much labor went into it, the quality of materials used, and the reputation of the vineyard) that is not a good wine.
Goal
It's hard to pinpoint what language this answer will say. But it should reinforce the idea that you could have an expensive wine (because of the reputation, labor, materials or some combo of the three) that is still not a good wine.