I would tend to agree in regards the actual value of the qualification that an institute like this could offer in comparison to CELTAs, TESOLs, etc. from renowned and accredited institutes. I know that these are not specialized towards exam preparation but they would still stand you in good sted to prepare individuals for the TOEFL or any other exam.

As CL said there are already plenty of people offering exam preparation in China. Therefore, if i was looking to buy your product I'd have to consider

What is it that your 'stand alone' product offers that theirs doesn't?

Indeed does your product offer something that i can't just replicate myself and use (in essence steal your idea)?

Equally, you're not an established brand, so appart from the product itself e.g. books, materials, etc. what am i paying for? - marketing, goodwill?

I'm sure that running a small enterprise doing exam preparation (i think Turnoi's comments about not limiting yourself to just TOEFL are very valid) could make you a bit of money but selling a training course and follow up product/brand to others is an entirely different matter.