I don't think you are being unreasonable. I'm not miserly, tightfisted, selfish etc. In fact quite the opposite. I buy £1 bottles of squash that go a long way to be shared out, I buy £1 boxes of ice pops that can be handed out and shared with friends. DS has a tub which is filled to the brim with sweets/chocolates/cake bars which he can do as he pleases between him and his friends (it is kept on top of the fridgefreezer so he can't reach it himself and does have to ask. I actively encourage him to share when he asks for things.
BUT
What I do object to is what one particular child who lives on our walk does, who regularly demands that my DS comes in for snacks, drinks, ice lollies, ice creams, money for the ice cream van, despite DS not always wanting something and saying no to him before coming in the house.
This rankles more, especially after the conversation I heard through the open living room window when DS and Child X hadn't realised I was in the living room and heard every word
Child X - Tell your mam that it's so hot out here that we need ice lollies, and if we don't get one, we will die'.
DS came in and I asked him if he wanted one, he said no, but I sharp let him know what I'd heard X say through the window, and had a conversation about people taking the mickey out of him, especially when the same offer isn't extended to him by said family.