So long as the vehicle isn't a rust-bucket, the vinyl will hold just fine. It does project a professional image, but don't get disappointed if the calls don't come streaming in. I haven't had too many calls that way, but I also have never MADE calls that way. But it something you have to do to look professional.
Make sure your name and logo are big, so they remember that when they look in the phone book for you.
Price sounds about right, too.