The cow is not going to supply you with milk for less than you are paying at the grocery store.
Besides that, think about getting 3-5 gallons of milk a DAY from the cow....what are you going to do with all that milk?
As a little experiment, I sugest doing this. Buy yourself some books on home dairy cows, and buy yourself a little stuffed cow. Do this for one month strait.
Go out every morning at 5AM, and get your stuffed cow out of the pasture. Lead your stuffed cow to where you are going to milk her. Now sit on a stool for 30 minutes with your stuffed cow, and read your books. This is the minimum amount of time a beginer would spend milking. It does not matter the weather, or if you are sick, or have an important meeting. NOTHING else happens before the cow is milked!
Now put your stuffed cow back in the pasture. Take your buckets of invisible milk (you didn't forget the buckets did you?) inside, and get them properly cooling. Just putting them into the fridge is not good enough. Your books will tell you all about how to properly handle the raw milk.
Now you can change clothes, shower, and get on with your day. Be sure you are home at 5pm sharp! Go out and get your stuffed cow again, and repete the entire process.
I'm sure you think I'm being a smart a$$, but I'm not. Honestly doing this is going to give you some idea what an impact on your life a cow is going to have. She needs to be milked twice a day, 12 hours appart, NO MATTER WHAT. You can be sick as death with the flu....cow still needs to be milked. Doing this exersize with your stuffed cow, is only going to give you a tiny fraction of the work a real cow will involve....but it will be a reality check, when you find out you cannot go on vacation, to a school function with your children, or work overtime....because the cow need to be milked.
I'm going to answer a coupld of the questions you asked.
Vet care....you need to learn how to give shots, and worm the cow yourself, as well as trimming her hooves.
If you need a Vet present for the cows delivery, send her off to market to be butchered. No I'm not kidding, and no I'm not a cruel person. She is going to cost you WAY more time, money and trouble in the long run than she is worth, if she cannot deliver a calf all on her own.
A lot of family milking cows are only breed every two years. Milk production drops offf some in the second year, but you probably do not need 3-5 gallons of milk a day anyway.
A good family milk cow, who's well cared for will live 20-25 years. A commercial dairy cow is lucky to see her 5th birthday.
In all honesty, if you want milking animals, serriously concider looking into dairy goats. They will give a much more reasonible amount of milk. Another plus with dairy goats is they cannot kick your face off (yes, I mean the skin of your face clean off and laying on the ground).
I've seen (in person) a farriers face kicked clean off, and laying on the ground (by a horse). I've seen a woman who's lower jaw and cheek bone on one side were nearly gone (totally caved in) from a cow kick.
My Great Grandmother spent 12 hours in a manger, holding the horns of a formerly friendly cow, who very suddenly decided she wanted to kill her. It was 12 hours before some got home. Are you physically strong enough to do that?
By the way, you do not have to pasturize your milk like another poster stated. Raw milk is delicious, and very healthy for you. It must just be handled correctly, so bacteria does not grow in it.
Homesteading/Farming over 20 years