My alternator just started buzzing really loudly the past couple of days, to a point where I can hear it from in the car with music on. I'm assuming it's on the way out (along with the other half of the things on this car) so where should I be looking for a new one?

AutoZone has the new Duralast one's for a decent price and a good warranty or should I just go with an AC Delco remanufactured one? I'll post up a video tomorrow of the noise just to be sure that it is the alternator dying.