I've experienced the same thing with cars over the years. Some people will tell you whatever they feel is necessary to keep you on "the line". With some folks, money comes before the notion of keeping one's word. They may reel you in, or they may throw you back depending on their needs (not yours).
The bottom line: Don't count on a thing no matter how much time you've put into phone calls and other correspondence. Keep your options open, because the guy with the car you want is most likely keeping his options way open.
Doc
PS - I have had a lot of great experiences, too.