Just to add on what Dave said.
Roaches live years longer than crickets, so the turn around of stock wont be as much as crickets, if you have 10 spiders you buy a bulk tub you can feed those spider for months to come, even years once they start breeding.
Not many people wont roaches as feeders, it goes against every thing that is right.
Often when I tell people I breed my own roaches they tell me I'm made, and that they try to keep them out there house and I breed them in the house

.
Also there is not a huge amount of people who wont to buy roaches as feeders.
And if you have to look at over the last couple of years, there is more people who are breeding roaches than what there use to be.
A couple of years ago you could buy roaches from pet shops, but over time it has come to a end.