In some police academies, part of the training requires the officers to be able to estimate the speed of a vehicle to within 5 mph. of it's actual speed.
I live in Mississippi, so luckily (for now) I don't have to deal with smog inspections. However, I'm wondering: Isn't there a visual inspection that you have to pass?
Why don't you look on Ebay? Plenty of new and used assemblies there. I got a new assembly for $60.00. Used can be had for much cheaper. Or, how about a pick and pull junkyard?
Yes, it's always a good idea to disconnect the battery ground when working on your electrical connections. And, I second the suggestion of ZMan's alternator upgrade. Good stuff.