I would suggest you start raising as many insect varieties that you can if the cost for keeping your chameleon fed is a major concern. Not to mention you know what your insects have eaten before they are fed to your chameleon. I don't 100% understand your question either. Crickets are expensive so you want to add roaches to his feeding schedule? So you would be feeding crickets and roaches? If that's the question then yes you should add roaches and other captive bread insects to your chameleon's diet if possible. Since adult roaches are larger than crickets you would have to feed less of them per feeding than crickets. Although I think roaches grow slower and have fewer young over a given time period than crickets so in the long run they probably will not be cheaper than a mostly cricket diet unless you are raising them yourself.