Buy something that can't they get smaller as they used to be

You need a childhood story of scraping the father and mother first before you do this, you need to indirectly obtain information when something small they want, but do not recall. Does your mother used to be a very specific character doll wants but not allowed to her parents? Does your dad first wanted a toy pedang-pedangan but haven't been able to bought? Then you could buy it with a nicer version, e.g. larger dolls or the sword that is not a toy. Although it may indeed not be used, it will give birth to beautiful feelings in their hearts and at least will be a memorable display, in-room or at home parents.