What I do from HerpShop, when ordering, is work out what to order based on my needs, and the weight of what you can put in one box.
HS give you 220g of roaches in the box, so I get mostly adults, then fill the rest of the weight with smaller ones, just to keep the stock going.
It depends on what you're feeding. If you're feeding adult lizards, then just order as many adult roaches as possible. If you're caring for juvies, then get a few adult breeders, and plenty of the size you desire.
If you've got a nice heat source and everything setup for your breeding colony, then don't worry too much about shopping around for the best price. Since it's gonna be self-sustaining, then just buy based on availability, and ease of ordering.