While I am fuzzy on actual cost (this is my 4th kid, I have everything I need) the total of used 'stuff' amounts to 5 shirts, 3 nightgowns, 3 blankets, a 'castle' (basically a blanket on the floor but it is hers, no other kid is allowed on it) and diapers/wipes oh and backpack (serves as a diaper bag). She hasn't seen the inside of a crib (sleeps in 'castle' or in my bed) hasn't needed any stuff. Though we do own toys they are mainly for the big kids to feel useful. (shake the toy while I change the diaper, keeps your fingers out of the diaper stuff, doesn't hurt little El any)
Diapers/wipes are around 40 a month (projected, she is only 2 weeks old) which goes down as they hold it in longer (and can be greatly reduced by ECing)
The clothes are all half hand me downs I imagine you can find some hand me downs sitting in someone else's closet, that you can transfer to your own closet to use as needed. so you aught to be able to cloth a baby free. (washing them fits in my other loads, no need for separate ones unless baby is sensitive - most are not-they rub against your shirt all the time)
Of course I breastfeed, so add formula/bottles if you wont be.
Medical insurance can be a big add on...though not as big if you already have a family plan. (first three kids were no extra cost-different insurance at the time)...well baby checkups will be your copay at 1 weekish, 1mo, 3mo, 6mo, 9mo, and 1yr. (plus future years)
if you have a healthy kid you will luck out and not have any sick visits (I did three times..we shall see this time)
I was not working and still don't so no costs to care for the kid. Though I do recommend upping the expected food budget..because no woman should try to be superwoman and cook, clean, care for baby, and try not to sink into smelly spitup covered mess every day. So buy some convenience foods for the first month or so (or hire a maid) anything to reduce your own expectations. But make it healthy convenience..you will need your strength.
Oh and the most important device for a nursing mom...a pillow
no need for a 50 dollar pillow, one from your bed or couch (or two) will do fine.