I have a 3 month old daughter.
Food.....can of gentlease formula (because she wasn't getting along with the regular stuff) sets me back $25 a can. That lasts about 4 days. So, $125 a month for formula.
Water. Have to use filtered water with flouride. That is $1 a gallon. 6 ounces of water per feeding gives me ~21 feedings a gallon. I feed her about 5-6 times in a 24 hour period (once every 4-5 hours on average). So, it's a gallon every 4 days. $7 a month in water.
Diapers.......well, that is where is gets expensive. I change her diaper every feeding. Sometimes it is a 2 diaper change (she pees while being changed, or has a nasty crap that goes on the new diaper). I have had the occassional 3 diaper change before. Not pretty.
184 diapers will set you back about $40 on average.
Let's say there are 10 diapers a day on average (sometimes less, sometimes more).
That gives me 18 days per box. About $2.25 a day in diapers.
Wipes...don't use them when she pees. Just when she craps and lately things have been a little softer than I would like. So, I have been going through wipes like crazy. Good thing they are cheap. Let's say 10 wipes a day. A box of 800 is $30. So, only $10 a month for wipes.
Just feeding and changing a kid will set you back about $210 a month.
Then there are the doctors visits. When they are little, you are in a lot for checkups. 1 week, 2 week, 1 month, 2 month checkups.
Miscellaneous other things add up to. I've had to get items such as: saline solution because she is congested, childrens tylenol, gas relief drops. All little things that you would never think of.
I'd put the bill at closer to $300 a month right now. It is only going to get more expensive the older she gets.
EDIT: Daycare........don't even want to get into that. It can range from $800 to $1,500 depending on the childs age and where they go. Right now I have family watching my daughter. I pay my parents $100 a week for watching her 3 days. My wife's mom does it one day a week and won't accept any money; same thing for my wife's cousin.
So, I am lucky and only pay $400 a month. That will go up as gas prices rise. It's a 80 mile roundtrip haul for my parents each day to come to my place. As the prices go up I'm going to have to pay them more.