replacing alternator

[bucknbuzz]

It seems my alternator is knackered on my 2010 tdci 2lt diesel. I've connected the multimeters neg lead to the neg battery terminal and positive lead to the postivie terminal of the alternator and I get a reading of 12.34amps, which is the same when both leads are on the battery terminals. When the engine is running, there is no charge going to the battery. I'm on the verge of trading this unit in so am looking for a standard unit to keep it going. Where would I find a reliable recond unit, or even 2nd hand unit? I've found the video online showing the process, that's not an issue, just the sourcing of a replacement unit.
cheers
B.