Hi! I get most my beardies greens and veggies from the organic food dept. at my local grocery store. Some people grow their own. Collard, turnip, and mustard greens are easy to find. Veggies can be obtained the same ways. Butternut squash is a big hit with my dragons. I pretty much buy everything at the local grocery store in the organic food dept.
As for live food: I get super worms and wax worms at my local pet stores.
Phoenix, silk, and butter worms, are easily found online. I use mulberryfarms.com. For a young dragon, phoenix worms are a great staple, they are packed with calcium so you don't have to dust.
My dragons don't like silkworms but they are both over a year old and 18" long so they get superworms as a staple. I don't recomend supers until your beardie is at least 16" long.