Itchy is probably a good source for you. In general, be wary of economy rebuilt units. Here's my story:
Winter 1994. Against my better judgement I was boosting a Chysler Lebaron turbo when it was -20 out. It was 9:30 at night at work and the guy needed to get home to Oshawa. When the cars were hooked up my voltmeter went way negative, but the guy started cranking his car for 30 seconds anyway

I tried to get him to lay off but I couldn't. Anyway that even lead to the eventual failure of my original alternator six months later. I choked when I priced a Toyota OEM (was it $600 or something?) so I went with a rebuilt unit for $150. That POS lasted 2 years (I'm very careful with the car except for that one boost). I then went with a Toyota remanufactured unit for $300 and it lasted fine (until the car went to heaven...)
Not all rebuilds are equal! Also if someone needs a boost, call the Automobile Club!