Yeah, I agree. I wouldn’t NOT buy a theme just because it had 0 sales. In fact, I would be more inclined to buy it with less sales because it means fewer people will have the same website. I think your other themes are just better, in my opinion and people are purchasing those.
Also, I would continue waiting and seeing what happens. Maybe try and promote it a bit on Twitter and stuff. Hope you start getting some sales soon! It is a great template!