If you were to do it ( make and sell plans). I think people would want something simple, cheap and easy to build. I think you will find alot of people who try this are nooby's. So you would want someting easy to start with. And a list and cost of where they can get all the parts with out running all over hell looking for them.
I would love to see some more plans out there. With some helpful people on the other end of those plans too!