The question is whether you need a herd of goats for a dairy or simply one. Many beginning farmers mistakenly think they need a herd, and have visions of selling the dairy products to provide an income - but are often surprised by the time, effort and money required to accomplish it. Then they're stuck with too many goats, too much work and not enough market for the product. Our little Alpine/Oberhasli goat, Zelda can produce enough milk for all the goat cheese we can eat each week. She must be fed, watered and milked twice a day - I repeat, MUST be milked. She needs a shelter, of course, but also social interaction. Goats are very social animals. We have Zelda and a buck, Arturo - but since she can't be with Arturo all the time (for breeding management reasons), she has sheep to play with. We're also about to get a wethered goat (Cashmere for the fiber) and he will also be a nice buddy that she can get attached to. If you're going to keep a single dairy goat, it does need friends.
Zelda is young and new to being milked, so it was a two-person operation at first - Maddrey at the "business end" while Frank kept Zelda's mind busy with a little treat bucket and lots of head scratches. But Frank built a little goat stand this week, and now Maddrey can milk by herself.
Frank always likes to make things a little fancy and practice his hand-carving, too.
The milk is then filtered (get high-quality stainless steel bucket and filter pan) and goes immediately into Ball jars and into the fridge until there's enough for cheese. We get about a quart of milk a day and a gallon is just enough for cheese.
So if your goal is a farm that is, first and foremost, self-sustaining, start small. You'll get the experience, understanding and knowledge you need to decide if you want to go bigger. But as Frank says, you don't own dairy animals they own you. We have discovered that small is plenty.