[s-cars] Voltage Regulator

[everett2487 at adelphia.net]

So I found out I needed a new regulator so I checked my new version of ETKA after getting the part number off my alternator.  It turns out I have the 110A BOSCH (PN 054 903 015 L) and the regulator for it (PN 034 903 803) was quoted at $175!! from the steeealer.  I'm not sure if the dealer in Roanoke, VA is the stealer to rule them all, or if i happen to have the alternator with the most expensive regulator of the 3 possibilities since other guys said they have gotten them from the dealer for under 50.  I figure I will call around to a couple other dealers, but do I have any other options?  Someone mentioned getting one from napa but it was a hassle for the audi guys to figure out what regulator worked and I can't imagine napa haivng the exact one I need.  
Which brings me to my next question, is it possible that the regulator for the BOSCH 120A alternator could work for mine?
Thanks guys,
Chuck
'93 S4