Valeo and Bosch are interchangeable, except for the pulley!
So if you have Valeo, you can switch to Bosch as long as the Bosch comes with the Bosch pulley.
Vice versa for Valeo.
I'd buy the brand-new
Bosch AL0703N for ~$230 (don't touch the rebuilt):
BMW Alternator (120a) (New) - Bosch AL0703N - Free Shipping