[Kodak]

I think I might need an Alternator, my Battery light came up a few times, Battery was already changed once by BMW, so I don't think its the battery, I thought it could have been that my key Fob might need to be recharged since I rarely use my spare.
My question is if it is the Alternator, is a Remanufactured one good enough or is a brand New one best ? Any recommended sites to order an Alternator if needed ?
I have a 2006, 4dr automatic ,sedan ,325xi , completely stock.