Bearded dragons can be fed easily and inexpensively with the right plan. First, stay away from crickets. They stink, make noise, and die too quickly while waiting to feed. Some places are selling different cricket varieties now and some of these are extremely aggressive...like little insectoid piranhas.
Dubias are the way to go as the primary food source for babies and the primary protein source for adults. Get a little critter keeper, put in top of something that puts off a littleheat, and invest $30-40 for a small colony. This one time purchase should be sufficient to keep your single dragon with dubia for it's lifetime. Supplement as needed with mealworms, superworms, waxworms, etc. but these should not make up a regular part of the diet, that's what your gutloaded dubia are for... they are perfect.
Do you cook? When you're chopping vegetables up for yourself, chop a little on the side for the dragon. Throw your scraps into the dubia colony. If you don't cook and even a quick wash and chop is too time consuming, buy a bag of prewashed dark leafy greens each week, it's not much, and throw some in. A whole head of dark green lettuce is 99 cents but you'll need to give it a quick rinse. Buy some other vegetables or fruit when they're on sale. Your dragon will get a variety of veggies this way and it'll be inexpensive. Yellow squash, zucchini, shredded carrots, strawberries, blackberries, are all very inexpensive, easy to prepare, and are top on beardie's preferred list.