I have to drive about 45 miles to get organic feed, so I try to buy about a month's supply and combine the trip with other errands in that general direction. I hate to drive that far for my feed, but I really don't like the idea of feeding them anything that isn't organic. The organic feed I buy is from Canada, so it too has traveled a ways.
The first three ducks I had were raised on conventional food for about 6 months before I found a source of organic feed. At first they did not want to eat the organic feed. I likened it to switching from junk food to health food. They could only go so long without it, as the weather was getting cold, so they eventually took to it.