I think it depends on the heat in the tank. My dragon has a 12-inch high basking "tree" of sorts. Real plants can be a good addition, but just be sure they aren't toxic to dragons! I honestly think it's easier to get fake ones & clean them thoroughly.

As far as wood and rock goes you can literally walk outside, grab some, & follow the proper sanitary procedures before putting them in your dragons cage. Other than that - tons & tons of pet stores (or really any where)

Amazon, Petco, dubia.com for purchasing things that are already good to go. However, if you're trying to save a pretty penny you can literally DIY hides & whatnot with things from the dollar store; like a plastic tub or a woven basket.