There are several retailers that carry a large variety of feeders for your Cham. It's important to review all your selections before deciding on the best staple food for your cham. Dubias are an excellent support feeder, even staple feeder if you can breed them quick enough, but keep in mind that an adult female dubia lays approximately 20 babies PER MONTH, so unless your cham only eats 5-6 dubia a day (small 1/4" size which birthed), you're gonna need more feeders than a measly 100 mixed dubia colony.
Please do your cham a favor and explore ALL realms of possibility with feeders, as diet with a good variety of insects contains a good variety of different nutrients. Per theory, if you fed the correct assortment of feeders for your Cham, you wouldn't need to dust your feeders with Calcium or Vitamins, but I would still suggest the occasional dusting to fill in the nutritional blanks so to speak.
If you want a hard producing roach, Lobsters or Red Runners (Turkistans) are much faster producers than Dubia roaches, although they can climb smooth container walls.