The Quarter/Half cow thing is great. Couple things you need depending on who you can find to get the cow from. Freezer space, Vaccum Sealer. A Guy I know raises free range grass fed cattle, he will then finish the cattle to your specifications. If you want them finished on grass, corn, oats, wheat etc... or any combination they will do it for you at no additional charge.
Finishing is basically the last few months before the slaughter they feed them something different to change the fat content/flavor profile of the meat. I don't know if finishing on other than grass reduces the nutritional value of the grass fed significantly or not. He does all the cutting AND vaccum seals all the cuts to your specifications.
It's about $4 per pound which is really pretty good considering the quality of the product. I just got my chest freezer this past week and will be talking to him about getting 1/2 a cow next fall. He is already sold out this season.
Here is a good website which identifies organic farms across the country. There is a shit ton of them and MOST will sell directly to you, weather it be beef, poultry, bison, lamb, veggies, etc... Once you find your preferred farmer the rest is pretty easy.
Hope this helps