I can pull a permit to process 1000 birds on-farm, but I can only direct sell, no farmers' markets, no restaurants.
Washington state has a permit like that. The customer
must pick up the bird at the farm.
It must be whole, (not cut up), and it must not ever be frozen (until the customer gets it home).
It is a $25 permit, and they are pretty lax. You can do it on a table on a grassy field as long as you have a way of keeping the whole operation sanitary.
The WA user's handbook explains it all. Pretty simple.
Perfect? No, but it is a step in the right direction.
http://agr.wa.gov/foodanimal/tempchickenslaughter/handbook.aspx