I feel your pain...only because I think I've dealt with some of the types of people you're talking about, over the last few years; mainly photogs all excited about shooting for me. We spend several hours on the phone or icq talking about everything involved, all the specs, pricing, samples....and then they disappear. One thing I'll never understand about this biz is the lack of common courtesy from so many people; it's not hard to just either say "no" up front, or even later on.....without disappearing or even worse, ducking you.
Best of luck with your search.