grain prices tend to get a bit lower in the fall, during harvest, if things are going well. Of course if harvest isn't going well, prices go up. look what happened with beans this year. the prices for bulk ingredients change daily, pre-mixed feed is not quite that volatile, but can change as the ingredients do.
there is really no predicting what feed prices will be at any given time of the year. if we could all do that reliably...us farmers would be rich, right?
i have to buy my poultry base 2 tons at a time, but they don't keep it for me. i have to pick it all up and i store it in a shed, in a grain truck (it is bagged). i have soybean meal delivered in bulk...2-4 tons at a time. i pay whatever the price is for the day.
my feed store offers a contract deal on some things like cattle tubs (I don't use them). you agree to buy so many through the winter and they will order them as you need them. they save by pre-ordering so many and just pass that along to the buyers.