Some things to consider are the live foods you will have to keep, and the amount that they require. Crickets, can be purchased over the web. For two beardeds this is the way to go, because if you bought from a pet store you will find your self sending there kids to college on the amount of crickets you need.lol. At a dollor for 12 you would be spending more for the dragons food then yours. On the web reptilefood.com sells thousand count boxes for $9 plus shipping. Dragons can eat up to 25 crickets a day each, more if younger. Super worms, wax worms, and mealies can be used once in a while. They also need a mixed green salad daily. Collard greens, mustard greens, escarole, endive, dandalions are all good dark leafy greens. Squash, sweet potatoes, mixed frozen veggies can be put on top of the greens. They also need a good calcium with d3, and multi vitamin suppliment to be dusted on the greens and live food. Water with a spray bottle or soaking. Most will not drink from standing water. Uvb needs to be provided. Repti-sun bulbs are good and give off uvb. Also a regular house bulb can be used for heat 105-110 basking spot 75-85 cool side.
As far as health. Make sure that the people were feeding them properly. Offering greens and live foods. Make sure that there poop is firm and formed and not soft. this is a sign of parasites. If kept properly they should have good weight to them.
If kept properly, and healthy dragons in captivity can live 7-10 years.
As far as housing goes. A good substrate is the repti carpet, or plain paper towels. People do use washed play sand, or wheat bran. I personally don't. I find the paper and repti carpet safer, cleaner, and easier. No risk of impaction. A half log or some thing for them to hide under to feel safe.