Adrian,
you have a PM.
My guess on the reason for it not being released on DVD and only being produced overseas is it has been religated to "Cult" status. That usually means they can't make enough money on it and nobody wants to pay the kings ranson for the legal right to reproduce it. I do hope I find a legitimate distributor, but my search so far has not yeilded much. I did send an email to Warner Brothers asking about how to souce the film on DVD, but no reply yet.
--Mike