Are you planning to teach in the USA or abroad? I am not sure of the demand within the US, but I know that in other countries business English has a high demand. I live in Sao Paulo, Brazil, and only teach business English to employees. Depending on the market, you can also make some pretty good money.
Not sure if you have business English teaching material. If not, check out my company's website http://www.englishkey.com
We have many open source content, so you can use all of that content online for free.
Also, if you are looking to do mock interviews with your students, check out a English teaching hobby project I have been working on. https://www.youtube.com/channel/UCxuARm ... rW_E1N-UlQ
This basically goes through each interview question and gives the interviewee tips on how to perform better. Also good for teachers. Hope this has helped. -Philip