From your side I understand why you are tempted, but from the side of an aunt to an overly spoiled 7 year old, you suck.
We are on a budget and while we can afford birthday presents, I really don't feel that it would be worth it. Anything this child gets is not good enough, the wrong thing, or is already owned. I'm glad his parents have been able to give him tablets, 3ds, game systems and $50 collectors transformers, but for some reason it is expected that we buy accordingly.
So we will find something reasonably priced that he will just throw in the corner and tell us how much it sucks, just like every year, because listening to a child throw a tantrum over a present is a lot less annoying than listening to an adult throw a tantrum from the lack of one.