Re: Bad Voltage Regulator?
I had to replace my alternator due to some internal fault in the unit - it suddenly started to discharge my battery VERY rapidly.
You can buy the voltage regulator separately or just the alternator or both as a unit but quite expensive items. I opted for a used but younger alternator from an Audi used parts dealer for a lot lot less.
I have a voltage dial in my car and it does as you describe upon startup but holds a constant voltage above 12v when the engine reaches normal idle speed. Have you tried measureing the voltage at the voltage regulator terminals?