I would have to agree that the first few years isn't that expensive. I have 2 boys and we are on a low (very low) income and I am happy (most of the time) with what we have. Both were (one still is) breastfed which saves alot. I think it it was worked out that a newborn goes through about $15 a week on formula? Our biggest expense is nappies. I am so sick of buying nappies. Cloth is an option but not one that I am wanting to take, too much work involved!
Childcare is something we have only just started with our oldest. He now goes to preschool 1 day a week and with 100% of the rebate it still costs $17 a day. With out it its $51 a day! A friend of mine is on a much higher income (about 70k a year) and I think gets about 30% rebate on childcare.
I like dach's idea of trying to cope on one income for a bit to see how you go. I personally think that mum should be home with baby full time for at least the forst 6 months if not the the first year, but thats just my opinion and by no means do I jugde anyone who chooses childcare. I just kinda figure why have them if someone else is going to raise them. You miss out on so much.

Be prepared to cut back on a lot of things to make it work, your bills are only as high as you make them.