Getting your own repaired is the best bet,most repairers give a warranty(ask first!!) at least you know what you have under the bonnet when it's repaired.A car dismantlers alternator could be on it's last legs(warranty unheard of)I've been there&done that!
The reconditioning of the old one is probably the best bet. There are probably a few variants at least you know once repaired the original will definitely fit back in.
I know the altenator on my passat tdi is rght at the top front of the engine, could be a handy enough DIY job to remove and replace.