10k, since I only have 7 ducks, custom feed is not something I can do. I did call a feed mill about blending some and they want you to order 1 ton at a time :P
I am relying on bagged feed from Big R (meat/game bird blend) and supplementing with anything I can grow in the garden, minnows from my pond, and duckweed.
I have seen ads on craigslist from someone who custom blends organic feed and sells surplus. It pops up from time to time.