Crickets are the easiest and most readily available and cheapest feeder insects for dragons. They are quite nutritous for them as well provided they are properly gut loaded (feed either store bought quality gutload about 12-24 hours before feeding to dragons...or feed mixed greens, crushed dry cat/dog food, dragon pellets or fish flakes (or a combination of the dry material with fresh greens, slice of orange, potato or squash for moisture)
A staple of crickets for baby dragons is fine. Adding other insect feeders such as phoenix worms, small butterworms, small to medium silkworms and hornworms, certainply provides a good variety. As your dragon gets bigger (say 12-14" or more) the larger butterworms, silkworms and hornworms can be fed as well as superworms.
Roaches are fine too though some species do have a hard shell and get too large as adults, to feed to even adult dragons (ie hissing roaches) The species you mentioned I believe is one of the better to feed to dragons. As with crickets, feed appropriate sized to the size of your dragon (space between dragon's eyes should equal or be greater than the length of the cricket or roach).
I feed a variety of insects...crickets, superworms, butterworms, silkworms and hornworms...though my staple insect for my adult dragon is superworms (this is only a small portion of what I feed, since she is an adult. I feed about 80% greens daily with a few superworms or other insects.)
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PHLdyPayne