I have 2 beardeds, And pet wise id say go for it, they are amazing!
As far as price, thats a little steep still because the 20 gal will only work for a 2-4 month age dragon.Any older will need a larger enclosure, that will have to be purchased or built.I got my baby "citris" male at Repticon for 30$ from a breeder.The one pictured isnt a normal color either. So thats a plus.
A 16"t 48"w 20"d enclosure will hold one adult male bearded ok (a little larger would be better) but that will do.
At that age/size it shouldnt be fed anything larger than 1/2" crix. it will probably eat 6-10 once around lunch time. Usually their schedule is: wake up, bask, eat, bask move around a bit, then sleep.
Mealworms shouldnt be fed very often at this age, and superworms of corse shouldnt be fed at all until adult.(others will say a juvi can eat supers, I say no)thats your call. Vgtables and fruits should be added as well of a fair size. and should be increased with age.
I also use the zoomed juvi beardie pellets. But ive never seen a dragon that small eat it.
As far as the sand issue, that substrate in the pic is definetly unsuitable. Unless you like taking risks(or if its fed in a seperate container)But i still wouldnt use it.
If you just want sub.The best to Use is exo-terra riverbed sand for turtles, It is the absolute smallest grain avalable. I have researched this. If this is used, pay close attention to feeding time in the beginning. Some dragons are accurate and others are not. If you notice its getting sand when he eats..Remove it!
Or hand feed or use a seperate container.
They are very personable if you Make an effort to tame it. the more handled, at a younger age the better.Getting a younger dragon will make you way closer to it. I wanted an adult in the beginning too, Now i will never get a adult unless its a rescue.
The main thing is Remember that any Info(including from myself) are Personal views unless info is sited, and can be "tweaked" to fit your liking.
Not to brag, But i can answer ANY questions you may have(if you have any) in every aspect or in all views of the question(seems that there is dominate views of All main questions like substrate, feeders, lightbulbs, taming ect.)
I have super researched these animals.
As stated above, Georgia bearded dragons care sheet is great i baught my female BD from them.
Sorry for long post..Hope it helps
Here is a pic of myne at almost 11months old.