Wow! That is a very optimistic goal. I started milking last March, and am still learning how to make cheese. You must be planning to make a LOT of cheese! Our LaMancha goats each give me 10 cups of milk once a day. If I milked twice a day, I could get 35 gallons a week
per goat. That can build up very quickly. I'm thinking with 250 goats that could amount to 8750 gallons of milk a month!!! That Is a LOT of milk!
I don't know how it is in Washington, but here in Texas, the laws are very restrictive, when it comes to selling raw goat's milk, or products made from raw goat's milk. If you haven't gone through the expensive, convoluted certification process, you can only sell your milk and it's products on the farm.
Then, you need to think about marketing. Again, I don't know how it is in your corner of WA, but here, in East TX, people aren't interested in paying for the extra cost of organic food. About a year ago, I was trying to sell our Free Range eggs (not "organic", but soy, and GMO free), for $4.00/dozen. People were telling me they could get eggs for $1.50/dozen at the grocery store. So, low price is more important than high nutrition.
You said you are changing to pure bred Nubians. I may have miss it, but did you say what other breeds your current goats are crossed with? Sometimes a cross can produce higher fat content and quantity. Sort of like crossing a Boer meat goat with a myotonic goat giving you maximum meat to bone ratio.
It's good to have you here on BYH. I look forward to learning from your experiences raising goats. For, as we know, we learn from our experiences. Here, on BYH, we learn from the experiences of other members as well. It's a win/win situation.