First off when picking out a Bearded Dragon make sure you take a good look at it first. Check to see if it's alert with wide eyes(unless its sleeping Dah or basking)and when its pick up it should show some movement and alertness. Check and see that its body and its tail is rounded.(not to many skin folds)
After you do that check to make sure that the little guy has all his fingers and toes. Check the lower jaw for any crusting. After handling check and see if they have mites.(either on your hands or on the lizard) The most important thing is don't buy any pet from a pet store owner that doesn't take care of his or her shop!!!!!(If its dirty and the pets dont look happy get out)
Beardies live to be up to 10 years old so remember its a 10 year responsibility!!!!!
If you would like to buy one Bearded Dragon try getting a male(although its hard to sex a Beardie at an early age). During breeding season the female's present a high risk of becoming eggbound if they are not bred. Single males have a better chance of living to an old age then females.