You can get by with an extremely high female to male ratio. Of course the bigger question is how many nice males you have available since there's no need to breed any runt males.
I'm hoping to eventually use them as feeders but not too much in a rush. My main feeder roaches right now are lobsters, I do have dubia and discoids too but they numbers are still low.
I didn't really get the ratios and sex I was hoping for. ended up getting 3 mature females and rest are nymphs with one of them being a male. Guessing I'm going to have to find a good source online for more.