I haven't kept them myself but I care for 30-200 at any given time at work.
Feeding:
Greens every day; kale, dandelion, mustard, chard, collards, escarole, etc. romaine is okay but i wouldn't recommend it as a staple. In addition to the greens, squash, bell peppers, carrots, mango, berries, and melon are all good things to make the salad less boring and give them a bit of variety once or twice a week. Make sure all fruits and veggies are chopped up into bit size pieces. As far as insects go, babies eat around 20 appropriately sized crickets or dubia roaches a day and adults 8-10 appropriately sized crickets or roaches a day. Other good feeder insects include meal worms, super worms, wax worms, earthworms, and tomato worms as well as wild collected grasshoppers and moths if you know that they came from an area where no pesticides were used. Use calcium and vitamin supplements daily for babies and ovulating females and weekly for adults, personally I like repashy's calcium plus. The food cost will vary on your local produce and bug prices.
Cleaning:
The cage should be spot cleaned daily and the entire substrate should be changed out every six months or so or when it starts to smell.
As far as personal experiences go, I love beardies and I think you'd be hard pressed to find another lizard species that has such a favorable combination of charisma and ease of care imho.