A wise man once said that knowledge is power. However, a wiser person said that the application of knowledge is power. The Internet is certainly the dawn of the information age, and what the Internet loves most is information. You should be prepared to share information about your business and even how your products work in order to win trust, influence and customers.
There will come a point where you may decide that the quality and value of the information you wish to give you such that it no longer qualifies as just information but is teaching. Many websites are now set up to train people are using a teaching based website which may include charges for the access to information.
WordPress is a very suitable platform for producing such learning type websites. Firstly, there are a number of very good membership plug-ins which allow you to limit access to content depending on membership level which may include the requirement of payments by students. There are also a number of plug-ins that allow you to organise information into courses, rather than simply building pages at within WordPress and organising them yourself.
A quick search for photography courses will provide you with a great list of people who wish to make money from this hobby/profession. You can search for many other common subjects such as dog walking, giving up smoking, hypnotherapy etc.
As with everything on the Internet, more niche or subject matter unless people may be interested but less competition then there will be in providing them with service. As with all things on the Internet you will not be able to build it and they will come, it will still require marketing and promotion like a normal website.
The biggest cost in setting up such a website is the experience and knowledge gained that can be then distilled into a number of courses. After you either have the ability to show others how to share in your knowledge are not. If you can explain to a stranger in the pub subject that you are interested in promoting, then I will consider you have a reasonable chance of succeeding online. People buy from people they like, and when it comes to teaching sites, this is truly the case.