I was reading about this all last night and from what I am getting I think the answer is to get a few hundred mixed sizes and leave them alone as much as possible for 3-4 months. Then weed out the males to establish a 1:5 male female ratio.
Set-up should include egg crates, heating pad, soil moist, tote, lid modified with a screen. Food can include, dog food, oranges, oatmeal, fish food, supplements you would normally dust your feeders with can be added to the dubias food in order to gut load them with good nutrients.
Now if someone would chime in on the best place to order 1,000 dubias from I'd be ready to get a colony too myself.
Mike