I know that meal worms are the cheapest thing to buy to feed your beardie but they are not very nutritious and are mostly hard shells with little inside. You can get crickets or other worms online for way cheaper than the pet store. If you buy them in bulk they are the cheapest. You can get 1000 crickets for only 20 dollars from
http://lllreptile.com/ that may seem like a lot but if you have a young dragon they should be eating anywhere from 30-90 crickets a day! so if you do that math that is only around 2 weeks of food. Do you dust your mealworms with calcium or a multi-vitamin?
Phoenix worms are also cheap and very healthy for your beardie
http://www.phoenixworm.com/servlet/StoreFront
check out
http://mulberryfarms.com/ for butterworms, silkworms or hornworms (if you have an older beardie)
Also make sure to feed things like butternut squash, collard greens, mustard greens or turnip greens. these can all be found at any large grocery store.