I have the lobsters and they are so easy to keep and all of my dragons love them. It is so funny that you just posted this because I was just going to post about crix and never buying them again. I have been buying crix until the roaches got going but I think I'm going to get some silkworms to try. NO MORE CRICKETS! It has been so humid here and I just lost 2000 crix. Roaches love humidity!
Anyway, I recommend starting with 100 adult roaches to get going. I started with 40 and I must have 1000s of babies in there now. I just have to wait until the grow a bit before feeding time. They have no smell and are so easy to keep. They are actually cool to watch. I have them in a 10 gal. reptile tank w/ screened lid and Vaseline around the top edge. Vaseline stops them from getting out, I haven't had one escape.
Draw back is that they are very good climbers. I supervise the dragons while they eat and actually throw in one at a time. It's good interaction between you and the dragon anyway. If you were to dump in the roaches and walk away, who knows were they could end up.
By the way, the ones at Mulberry Farms, the Orange Heads are not supposed to be able to climb glass like Lobsters. They might be better for ya.