I bought the alternator from a company called Alterstart
(<--click for website).
They list it as $250 on their site but they sell it on ebay for $200.
I've only had it on for about a month, but so far so good. I've got to plow with the new setup too. It works great.
First pic shows the new alt. next to the old stock alt. It's not huge, but it's a lot bigger than the stock one.