But, who is doing the actual buying?

When I take my daughter to the candy store, it is she who is doing the buying. Even though she is all of four years old and I am forking out the cash. When we take her to buy clothes, I do the buying. She has an opinion, and she voices it but is routinely ignored. 

It is of course different with our elder daughter, who is "11 going on 21". We have to listen and sometimes she wins and sometimes we do. In all cases, of course, I am paying the cash. 

When a business purchases goods, many people are involved in the purchase decision. And their roles and power they wield also varies from case to case. 

With my younger daughter in the candy store, she is the consumer (User buyer in jargon), Evaluating buyer (she decides which candy gets bought) and also Economic buyer (the boss-man; who signs the PO). Like in an enterprise, the man who forks out the cash, often has no other authority or influence other than signing cheques.

So, what is my role in that case? I suggest, and only half-jokingly, it is that of the "blocker"; I try to avoid the corner of the shopping mall where the candy store is. In all enterprises there are people who will try and block you (or the candy-salesman) getting in touch with your prospective buyer (or my daughter).

But, when the same younger daughter is taken to buy clothes, we decide the budget, the colour, the type of dress, the accessories.. the lot. She virtually has no role.

Knowing who is involved in making purchasing decisions is key. After all, you don't want to waste time and money selling candy to me, do you?