I agree with the others, its what ever you let it be.. We made the decision before we had any kids that we would not do private school as we wanted at least 3 kids, so we looked at schools when we chose where to live. I buy a few extra bits of clothes to top up DD2s wardrobe as the girls have been different seasons. I Op Shop where i can, use Gumtree and local pages for bigger stuff. We upgraded DD1s car seat so DD2 could have the babyseat. This time round we will be getting a second (larger) car, but that was always in the plan so we have been saving so we will have the cash for it. My cloth nappy stash will be on to the 3rd baby with just a few binned and replaced along the way, I reckon i have spend $800 on a pretty big stash.. but thats nothing to the cost of 3+ kids in sposies.
I have a budget of about $200 for the bits i need for belly babe, a new change mat, a few new towels, and I'll get a few clothes bits if bubs a boy (not a whole new batch by any means).