I am willing to give up my first born for a Universal Geneve Nina Rindt. The ROI on the first born should be around 200,000k USD over it's lifetime. These unrealized gains will only be realized once the child gets it's first job. Willing to negotiate terms of trade.
Does not sound like a good trade to be honest. You have to put up with their nonsense for a lifetime and I think your expenditure estimate is a little optimistic. I think the watch will bring far more pleasure than any kid will. If you have a dog or even a goldfish to trade you might get lucky