It all depend on the aquarium/fish shops you go to. Smaller shops usually won't even bother to care sharks - because they consider them to be a speciality fish.
Your best bet to get a shark locally is to check with the bigger chain Aquarium shops. Often times even if they don't have sharks in stock - they can usually order them (note this is were you as the buyer need to be aware of which kind of shark your looking for). Still it's sometimes difficult to figure out the names LFS(Local Fish Shops) use compared to the given common name of the sharks.
Also if you don't mind have your shark shipped - you can check at several sites online - but in that case -it's usually buyer beware.