Yes - Bull Sharks are impractical for the vast majority of private shark aquarists. Hince the reason for the 10K price tag. Basically if you can afford to pay $10,000 for a shark - then you should also be able to afford a shark pond/tank that is more than 100,000 gallons to keep it in.
As for Short-tail Nurses - they are in the same family(Ginglymostomatidae-Nurse Sharks) as the Common Nurse & Tawny Nurse sharks. However they are much smaller than either of the other two species. The maximum record size for a Short-tailed Nurse is about 30 inches - and that was from a specimen that is known to be more than 30 years old.