Depending on how much time you have on your hands, it's better to start small for money sake, but I got some great deals on a large number of roaches in the last few months, so I went for the "more is better" realm.
I keep around 200 or so B.dubia, and around 500 B.fusca hybrids, but they breed very slow at 78-80ºF. I see many more dubia nymphs compared to fusca nymphs however. I started with 100 dubia around two or so months ago, and 400 fusca not quite a month ago. But, once more adults mature I'm sure I'll have a heap of roaches on my hands. Then again, I don't mind the slow reproduction, I only have 8 scorpions currently and I like having the colony as "pet-like" until they go wild breeding. Last week I got 3 subadult giganteus and several nymphs, so I will let you know how they go in a few months.