FinchLover&Breeder
All right, that's good. I don't have experience with bearded dragons (or any omnivorous reptiles, in that case); however, I have kept several reptiles over the years. I'm most experienced with green anoles and broad-headed skinks.
Do you have room for a ten-gallon tank, as well as the one for your bearded dragon? If so you can buy crickets in bulk and keep them in the small terrarium until your bearded dragon needs to eat them. I bought 500 small or medium ones for under $20, and they lasted for quite a while.
Just fill the bottom of the small tank with sand and place some paper towel rolls around, and then dump in the crickets. You can feed them table scraps like lettuce and carrots for hydration and ground unsweetened cereal and oats for nutrition. I find that they actually don't stink too badly on this diet, provided that you sift the dead crickets and old food out every few days. Still, don't keep them in your closet, or your clothes will start to smell like crickets. I made that mistake several years ago, and I swear I still occasionally catch the scent of cricket in there...
IMPORTANT: do NOT feed crickets calcium-fortified food until gut-loading 1-2 days before feeding. All of my crickets were dying, so I asked a cricket vendor at a reptile expo why, and he said that the calcium-fortified food made the crickets' exoskeletons too hard, so most of them couldn't moult and therefore died. I stopped feeding them the calcium food after this, and they stopped dying. Calcium also seems to smell a bit weird.
Breeding crickets is a little more difficult, but has the potential of making it so you never need to buy feeder insects again. I succeeded at breeding them using the method below; however, the pinheads died due to a humidity and fly problem. I think I've come up with an idea to stop that from happening again.
Fill a shallow container around the size of your hand with half an inch to an inch of sterile dirt. Spray water on it until it is somewhat damp, and place it in the cricket tank, making sure the crickets can get in and out of it. You will have to keep the dirt in the container damp, or eggs will dry out. To increase the number of eggs laid, only feed your bearded dragon the male crickets, making sure to leave 2-3 adult males. If you run out of extra males, then feed juvenile females. Females have an ovipositor (looks like a black tube in between the fork of their tail), while males do not.
Once eggs are in the dirt, place the container in a plastic container about the size of a shoebox, and put the lid on. Open the container every day and make sure the dirt stays damp. Once the crickets hatch, you can start putting their food in and replacing it if it gets moldy. Once the crickets are 3/8" long or so, you can move them to the regular cricket tank.
It would probably be a good idea to make a lid with a very fine mesh so air can circulate without tiny flies getting in. If you keep this container indoors, flies shouldn't be much of an issue.
I hear mealworms are easier to breed and take care of than crickets, although they are quite a bit fattier. They might be fine for a bearded dragon, though, considering an adult beardie would also be eating quite a few plants without much fat.
And if you ever want to make a bioactive terrarium with a custom background, I'd recommend looking at
SerpaDesign's videos in the Vivarium Builds and DIY Backgrounds playlists. Most of them are for tropical species, but use a different substrate and plants and the idea's pretty similar.