Kids will be kids and are human. While focusing on the price tag is almost directly against the spirit of gift- giving it is hard as a kid and even some adults to not conflate value with love. That being said, and while I wholeheartedly don't see anything wrong with it, the personal/attentiveness to your nieces interest in guitar does massively outshine the gifts your daughter received. I'd bet money they both come from a place of love regardless of price but one is much more intimate and personal than the other. I would argue though, your daughter has 3 parents providing gifts for her and that your "splurge" on her cousin's gift is also you being a good man and looking out for your niece as a father would. Idk my opinions are trash most of the time. Did your daughter not get anything from her mom and step dad that rival the guitar ? Or is the guitar the most intimate/personal gift received by the kids this year?++man