It depends what type and brand of food you are buying, but most small jars of baby food cost around $2.00. These brands include Gerbers and Motts. Formula for milk costs around $2.00 a package also.
Starting off with formula, the cost of ready to pour is about $7 a can, you will use at least one can a day at first and then more as the baby grows. Jarred food is about $1.50 for 4 and you will still be using formula.
Cost of baby food is going to vary depending on your child's needs, formula can average over $100.00 a week while baby food will run you anywhere from 30 cents a jar to over $1.00 a jar.