Huh. Your children are... wonderfully peculiar!
I wish my kids wouldn't want so much material possessions, and just be content with life in general.
Mine want stuff they don't need all the time. Video games and toys galore. Of course, I don't give them any money, including allowances (because they won't be getting that in the real world either). All I do is ask them, "And how would you earn the money to buy that?"
With a little bit of guidance and coaching, I would point them the way towards some chores and jobs they can do to earn some money, and when they save enough, then they can go out and buy it.
That's... basically it for me.