Alternator going bad?

[PeterBergin at aol.com]

Hi guys, need a quick opinion on my alternator.  I replaced the  brushes and 
regulator at 160k (it failed with no warning).  Now I have 200k  and I have 
been hearing a very slight wine and have a little bit of wine in my  radio.
 
Today after restarting the car after a brief stop at the mail box, I had  the 
idiot lights on very dim at idle and normal at speed.  The volt meter  was 
around 12 volts with the AC and lights on.  Increasing the rpm's the  meter and 
the gauge in the AC controller both make a spike or jump to around 13  volts 
(jerky movement) up.  My guess is that alternator is about to go.  (the spiking 
continues when I blip the gas).
 
I have a 6 months old good battery with clean connections, the belt is old  
but tight.  I have not crawled underneath to check the connections on the  back 
of the alternator yet.
 
My inclination is to buy a rebuilt higher amp alternator and be ready when  
it goes.
 
I had the alternator fail on my old 5000 Avant at 250k, and it cost me $500  
to get it fixed out in the boonies 300 miles from home.
 
Any suggestions and where is the best deal for a rebuilt, I usually use  Blau.
 
Thanks,
Pete
91 Avant