$600 alternator... EFF!!!!

leaving school to grab lunch the other day my red battery charge indicator warning light was popping on every time i hit higher RPMs... EFF!  I knew exactly what was going on... the alternator was on the verge of "cah-put!"
So i get lunch and hop back into my car and the light is fully illuminated indicating that the vehicle's charging system is not delivering anything back to the battery.  I then head back to school to diagnose my failing alternator; luckily im enrolled in the auto tech program at the university.  So i grab a scan tool to see if i can get the alternator output voltage because im too lazy at the moment to pop the trunk, pull up the carpet and plastic battery cover to probe the terminals with a DVOM.  Fail... BMW unfortunately hides a majority of their obd-II features... the output voltage being one of them.  Next i break down and head for the battery in the trunk with the DVOM... just as i suspected the voltage read 11.93v... no charge coming from the alternator what-so-ever... even with trying to full-field it with turning on all the auxiliaries.
So? Whats next?  I assumed that the alternator would be $200+ to replace and i didnt want to buy one right then and there... so i headed home 25 miles trying to beat the drain of my battery... and... i didnt even make it close to home... the battery then gave up its ghost at 16th north in Lindon by the Lexus dealership... as the poor Bimmer puttered to a death I called the wife... busy at work... then the mom... not picking up (she never picks up)... and then the pop... success.  My dad came to my pitiful aid.  by the time he got from Alpine to Lindon I had pulled out all my air cleaner system removed the serpentine belt and removed the alternator from  the engine compartment (all of 15 minutes).  We rolled over to the nearest parts store to pick up the new alternator.  As we arrive we request the part and just to top of my sundae with a cherry they said it was going to be $600 for the part... i knew parts would be expensive but not $600-alternator expensive.  I then told them to calculate my student discount for the auto program at the university and the price was right!  It dropped down to $189.00 with the core included!  Life is good when discounts come this extreme!  All in all we made it back and i threw the new genny in and jumped the Bimmer and viola! Purring like a goat!  I was back on the road again.