In this article on accessibility, Christian Heilmann takes a look at the 10 reasons why clients don't care about accessibilty. Having dealt with this issue and read Joe Clark's book on accessibility, I know first hand that there are so many gray areas and a lack of clear reasons why sites should be accessible. Reason number 2 "There Is No Immediate Benefit" is something I had to deal with directly with a client.
It's really a shame that clients view accessibility this way, but the more immediate needs of site development seem to always take precedence. Having worked with the JAWS reader on a couple of projects, I know how difficult it is for an impaired user to view a site. Hopefully, in the future, a central methodology will be in place for implementing accessibility either through the browsers or from the development community.