I think you can really go as low or high as you see fit. When DS was a baby we had a lot of gifts from showers (registered for gifts) and hand me downs and we bought a sling and cloth diapers. The sling cost us $40 and the cloth diapers about $300 (added up from birth to potty training), but you can go anywhere from $150+ on cloth diapers and you can get a used sling for $10-20. Luckily our insurance covered all medical expenses 100% and I breastfed exclusively. DS started solids at about 10 mos and we never bought him any special food. He never needed whole milk because he breastfed well into toddlerhood and whenever we wanted something pricier for him we asked for them at gift giving occasions. We didn't buy a crib, crib bedding, etc because he slept with us and we got things like a swing, exersaucer, bouncy seat, etc as gifts or hand me downs.
Now does this mean that we spent a total of $340 for the first year or so? No, occasionally we bought him clothes and toys, and there are expenses like tylenol, prescription co-pays, extra laundry, extra utilities, gas, more convenience foods and take out for us when we were too exhausted to cook...but who really keeps total track? When you have a baby the baby slowly becomes part of the family and a lot of things just get put into family expenses. Things like clothes and toys can be minimal, especially at the beginning! Babies don't know if they have new or used clothes and they're much happier playing with an empty box and a tupperware container than with the flashy educational toy. And garage saleing is really fun! I think that once we get to school age (in the fall!) I will really notice more expenses though.
Also, I stay home so I save a lot of money on myself because I don't need a lot of clothes and other expenses related to working outside the home. With my earning potential I basically would have been working to pay for childcare AND I wanted to stay home. Since I'm home we save a lot of money on food (have time to cook) and we have one car that we only need to use occasionally (DH bikes). When DS was younger we had tons of playdates at each other's homes, library trips, outings to the parks, all of which are free! So for us and a lot of my friends with kids, the years up to pre-K/Kindy are really flexible as far as costs.