I frequently buy objects but I am not really an expert for that particular domain.
For instance, I recently bought some Bluetooth speakers but I was not sure about the brand and the quality of the deal I was making.
In those situations, I would certainly pay a few bucks to someone who is well know expert and is willing to give me advices on what to buy.
Personal shoppers are common on expensive objects, but I am thinking about something done on a massive scale. I think that Amazon would be the perfect place for making this working at scale
BTW, ranking personal shoppers is a clear machine learning problem