[rmah]

In my experience, contract software development client acquisition is based mostly on reputation, referrals and personal contacts/networks. The biggest risk that clients face is not the cost of the project per-se, but missed delivery and/or poor results. So, in a sense, what you're really selling is not technical acumen, but trust and reliability.

Yes, project failure can often be laid at the feet of the client. But, IMO, good professionals contract developers are responsible for pushing back on vague and/or changing requirements. Part of your job is to look underneath what the client says to discern what he actually needs. The goal should be to and deliver something that is both useful and fulfills the client's goals. All of this is, of course, easier said than done.