I wouldn't recommend buying from a pet shop as they usually don't care for them properly, and they get parasites, MBDs, they're not fed enough, etc.
But if you really want to know, pick up your feet and walk to the nearby one (or... drive, if you can drive, or whatnot) and check out the local pet store because petstore prices can be organic. Where I live the petland has sandfires for about 90usd, while petsmart, petco and plano pets have grey or 'normal' beardies for around 60.
Still, I would suggest looking for a breeder in your area that will let you see the beardies. I got two very healthy, fat and colorful beardies for 70 each.
I think it all depends sometimes 80$ sometimes more or less. You just have to watch what your getting ie buying. I havent boughten from a pet store I just go in them to see how they treat the beardies and what the substrate is, mine have all come from breeders and their prices have ranged from 140-250 $ for all of mine. I also am in the process of rescuing another beardie and will just pay the adoption fee from my local rescue agency here in Canada.
If your serious about getting a beardie though my suggestion is make sure you do all your research bearded dragons are alot of commitment they can cost alot of money food viv and so forth, vet visits, also they live to 10+ years some do.
I was just at Petco today and they had their baby beardies for $80. The Petsuperarket near me usually sells them for $75, but if they any color on them then they raise the price to $90.
You have to be careful with pet stores and other questionable places. They might cost less upfront, but might make up for it later. My $60 dollar dragons cost me several hundred in vet bills in the first months.
Where do u live? The best is to get it when they have the reptile EXPO. There's one coming up in Pasadina ca. Not sure where u live but this one is in November. I went the last day of one a couple of weeks ago since I wanted 2 of them I got them for 80 total. There beautiful color very healthy. All breaders best deals on lights, tanks anything. I suggest finding out when there's one near u.