You're trying to conflate two different problems. Your insecurity over your son's Xbox time isn't going to help teach him the value of money any more than it will educate him on fishing or sport shooting. If you want to spend time together, the onus is on you to arrange that.

Same goes for the whole "value of money" shtick too, honestly. Your son is playing Xbox because his life hours have been spared (by your hand!!!) from the virtueless misfortune of closing Pizza Hut every weekday at 11pm. Don't teach him the value of money, teach him the value of time. Buy him books about the director of his favorite game and support the passions and interests he latches onto when he finds them. If you try to launder all of your fears through the Xbox then you're no better off than where you started.