I wouldn't do it. People make a lot of money selling shares.
You get 1 gallon a week per share plus you pay to feed the cow.
the comment that Lactose intolerant people can drink raw milk without problems is hogwash.
How much milk does your family drink? When we had all 5 kids at home (7 people including my husband and I), we went through 1 1/2 gallons a day. Now with only 3 adults at home, we still go through almost a gallon a day.
We are giving the extra milk to a pig right now. We don't have this cow's calf and we can't use her as double duty (raising a couple of calves and giving us milk).
When our cow had a calf, we would get another to put on her. We would keep the calves separate from the cow so that she would come up to be milked twice a day. When we needed milk in the house, my husband or I would milk what we needed and then let the calves in with her to strip her out. If we didn't need milk, we would let the calves in with her when she ate. It worked well for us.
If you don't need a lot of milk, I would look into getting a goat or two. Goat milk is good as long as you don't have the doe with a billy. If you do, the milk tastes just like the billy goat -- really really gross. Otherwise the milk is sweet without a goatish taste. Our two oldest children were raised on goat milk. We had a Toggenberg (very sweet goat and easy to get along with), Nubians ( they have strong personalities) and La Manchas which have the elfin ears. They are a gentle goat too.
Sometimes I think that I would like another.