In Northern California where I live it is between $20 and $25 for 50# organic lay pellets or scratch, depending on where you buy it. Regular gas $3.49/gal in my remote area.
I think during the depression, folks in rural areas had more pasture/land and grew grain (or bought it locally for pennies) for their critters and/or the critters got every kitchen scrap there was and foraged for a part of their food. People like us weren't paying a premium for "organic," because most things were grown that way, and there wasn't a special designation for it.
I just visited a website that had prices for things in the 30s. A dozen eggs sold for 18 cents. Spring chicken went for 20 cents a pound. In today's prices that is equivalent to $2.75 a doz and $3.09/lb respectively. (I used 1935 as the year and adjusted for inflation.) That sounds about right for the current price of eggs (non-organic) at the store. Organic eggs would sell for $4-$5 here. I have NO idea what chicken sells for, perhaps someone can chime in with that information.