I'm not in this niche but have shopped for and used a megaton of themes. I would suggest getting a theme or plugin listed on wordpress. From what I've seen, it's not always easy. There is this panel of as*holes that has to approve it and stuff and will tear it apart and demand perfection down to the last holy SPECK, and they act like fkn wikipedia moderators. Lordy.
Also, finding crappy websites, building a mock-up, emailing the mock-up to them with a price works, but you have a sales ratio of like 1:20 generally with that, back when I did it anyway, and that was locally. You could always offer free website with the hosting and make money that way.
If you want big bucks hit up the money companies, there are methods here on bhw outlining that. One that comes to mind is auto dealerships, they often have crappy sites (the smaller outlets) but also the money to pay for a better one.. plus they drive a lot of leads online. Another one that just popped into my head is auction houses... good GOD do they have HORRID websites. Anyway, once you get one client like that, they start telling their buddies or their competition sees and wants one too.