For you to overnight an appropriate shipping container with a shark in it, you're looking easily into the three figure range. Online fish stores get shipping discounts because of their quantity. I'm guessing you don't have an active FedEx account? I have never heard of an online store taking fish, if they did, you would basically have to give it away, no money for the fish, and likely pay your own $125 shipping costs.
Unless you live in South Florida, Southern California, or New York, your chances of finding someone to take the fish go from very unlikely, to nearly impossible. The thing is, if someone wants a shark, why wouldn't they just hatch and raise one themselves?
Lastly to put it quite bluntly, have you observed catsharks at all? I know the idea of keeping a shark is cool, but catsharks aren't really a typical shark, they lay around, lumber around to find food. They are a lot like another cat, catfish.
To expel on the 'naysayer' bit, it's not really that we want to put people down. But more like reasons why we don't keep sharks. I think sharks and rays are cool, but at the present time, thousand gallon tanks just aren't a possibility. I'm sure for 99.5% of aquarist, it isn't as well.