Voltage Regulator

I have a 2000 Vr6, 115000 miles... about a month ago the car starting having problems starting, i was able to jump it a few times but within a few days it wouldnt even stay running, i would get maybe 3 minutes out of it before dash warning lights start flashing and the car eventually stalling... ive had some say the battery may have a bad cell, some say the alternator is bad, however no body has mentioned the voltage regulator, whats the likely hood that it may be just that, i would much rather spend 40 on a V.R. than $200+ on an alternator...my local autoshops dont have the equipment to test an alt. with the external reg like the VW. so thats out of the question.. is there any symptoms i could look for that tells me it is one or the other.. or will i have to just start with the cheapest part and hope for the best... thanks for any help. Robert S.