Many people are able to put up their own websites using site builders and templates these days. I would focus on finding a way to differentiate yourself. Why should you build them a site instead of them throwing one up in an afternoon?
Additionally, some of these people probably already have a website up. You need to articulate the benefits of having you redo it for them.
We’ve done it for our content marketing agency. We spent time customising the messages and we did get some clients from it but it has a VERY low hit rate.