My saanen buck is a pig he eats a good size flake am and pm.
Females I would say flake am and pm also. If they have pasture to graze sometimes then I would do one flake a day with the grazing pasture per alpine. In the winter I would give some grain each but not necessarily necessary.
If pregnant or lactating I would give goat chow at a min. Maybe mixed with milk pellets but when starting this always small amounts till they are use to it....1/2 cup each a day for a couple days then 1/2 cup am/pm a couple days, then a cup a day for a couple days, then a cup am/pm each alpine.
Hay prices are different in every area so hard to say what your cost will be. When I say flake this is off of full size bales and like 4 inch thick flakes.
You can also get alot of info from BYH (back yard herds) a sister site to BYC.
Hope this helps!