In a nutshell, it is much more complicated than you may think.
I am well aware that the complexity of such transactions and the annoyance they cause makes any dive shop reluctant to proceed with them. My post, sans smilies, was directed towards shops that don't respond to legitimate purchase inquiries. I'm the sort that gets a bit miffed when I politely say "hello" and don't get a response.
You are also forgetting that almost ALL dive shops sign agreements with scuba equipment manufacturers and are not permitted to sell outside their country.
No, I am not forgetting, I didn't know that all. Seems like an silly policy to me, but I'm just a diver, not a salesman.
Obviously, the best option for obtaining 'foreign' goods is to use a proxy agent to skirt the obnoxious red tape.
Cheers.
Sadamune