Hey I scored a slightly used 130A alternator for ~$90 shipped.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...item=2428900118
This will work okay with a stock crank pulley, big stereo, and electric fans. My charging system was fine before the fans with the stereo but the fan draw about 30A at full blast and that is hurting my charging system espically when the headlights are on.
If I was running a stock fan and underdrive pulley, this 130A would be fine. If you were going to run electric fans with an underdrive pulley I'd go ahead and run a 200A alternator.