HodgePodge, bless you, you made my day 
I have 4 DS, the oldest is 12.
As soon as one meal is cleared away, he is looking for more food. Or a snack, or a 'treat', or 'something to eat' aka chocolate, or dinner. Sometimes he comes and asks when dinner is going to be about half an hour after dinner - yes, he is almost a teen, his shoes are 2 sizes bigger than mine, he could do with a shave (
) and his 11 yo brother is almost the same.
So, feeding them costs rather a lot.
As do shoes that last a couple of months as best.
Clothes.
Sports.
Days out, cinema, petrol to take them places.
Passport fees for them all! 
Food.
Things they 'need' - their definition of 'need' differs wildly from mine 
Food.
Books, toys, iTunes credit (have you even heard of Minecraft yet? Or StampyWotsHisFace??)
Food.
'Tis all good fun though, but yes, not having them would free an awful lot of disposable income.
And that is before we spend £1500 on childcare/month.
Sigh.