I have a local rebuilder who does a great job of rebuilding alternators and starters. They have a one year warranty.
He uses improved solenoids over the Bosch ones.
There appears to be a shortage of rebuilt alternators on the market. I heard that Porsche sent their cores to a Bosch plant in Ukraine and are not getting any out of the country. I have two finished starters on hand and will have an alternator later this week.
Price is $150 plus shipping and a core to be returned.