I used to be like that. But being a nice guy on the internet doesn't give you brownie points anywhere. I wouldn't lie to the kid though, take advantage of his broken prior knowledge.
Nope, it doesn't give me karma. Like I said, I will rip off an adult. But if you sound like you are six years old and you have people jumping at you to try and rip you off, I will let you know.
I was a kid once and if my mom bought me shit, I wouldn't want people to take it unfairly. Adults though, they are smart enough to read before they start trading.