Hi there!
Don't bother with commercial chow if you don't already have it. If you do already have it, it's not going to hurt anything to use it up, though.
But- the best thing to feed your feeders is the veggies you're feeding your dragon! If he's young and not too into his veggies yet, a good way to sneak them in there is in the bellies of his bugs! I toss my guy's leftover salad scraps into my feeder bins and they gobble it up. You can throw in any of your dragon's greens (like mustards, collards, turnips, etc.) and any of the veggies (like green beans, peppers, squash, etc.), just remember to
avoid citrus and anything else that you wouldn't give to your dragon. Carrots are a good thing to toss in, too, since they have lots of moisture and will keep your roaches
hydrated. Just make sure that any food in the bin doesn't get moldy, cuz that won't be good for the bugs or your dragon! (AND-not that you would- but don't use dog or cat food because it's got too much protein)
Good luck!