I would certainly buy VN's here if they were offered.
Aselia the Eternal (family-friendly version, that's the only one translated),
(if the developer would translate the last few pieces - a couple endings and the "extras" scenes lack English translations), and [url=http://www.shira-oka.com/]Shira Oka (completely western-produced) should, as far as I'm concerned, all find a place here (though Shira Oka is already available DRM-free from Gamersgate and other places, the other two are available at, perhaps, lesser-known places).
I would mention others, but I prefer to keep it short and family-friendly.
EDIT: I don't know if
Portal (Rob Swigart's 1986 one, not the one from Valve) qualifies as a visual novel, or if it's better described as an interactive novel (though more visual than Zork, it's less visual and more text-heavy than any VN I've played), I'd like to see it here though (as far as I know, the DOS version is only available from one of the "Home of the Underdogs" spinoffs, I think Swigart himself still has the Amiga version somewhere though he's said that he doesn't have the DOS version).