It really would vary depending on where you live. Make sure you don't get any heat up rocks or pads as bearded dragons naturally deprive heat from above, not under. Heat pads and rocks will burn your dragon. I also wouldn't reccomended buying fake plants as bearded dragons can sometimes eat them, which causes compaction. I think there is a article on this site somewhere about safe plants you can put in a beardies tank. Branches need to be sterilised and not from your backyard as they could hold parasites or bacteria that may harm your dragon.
Honestly, stones and rocks aren't really that useful in a dragon enclosure. Your better off getting one or two climbing branches, preferably in the warmer end. It's good that they are high, but not to high so your dragon can bask properly. If you get lucky enough, try to get a branch with different leveling so your dragon can experience different tempatures if they desire. A hide is great to in the cooler end as they can retreat when they feel the need of security or are too hot. The best place to get your decor from is definitely the pet shop (one that is clean and you can trust) or a exotic pet store. I live in Australia, so I wouldn't know any stores to reccomend to you unless you live in Aus but I have personally heard exoterra is very good
http://www.exo-terra.com/en/index.php
Here's a picture of my setup just for a rough idea:
Hope this helped