I wouldnt recommend it. Even if you have been teaching English for a while, nothing is a substitute for a 'real' classroom TESOL. An online TESOL is just like paying for a certificate. You won't gain anything from the experience. Up to you.
> Karen,
Thank you for your comment.
I'm sure a real classroom TESOL would give me much better learning experience.
But if you have the certificate from online course, would the employer disregard it because you got it online? Do they even see the difference?
I would like to suggest the course I'm using right now. (to get a TESOL certificate)
http://www.linguaedge.com/
It cost me about $150 for a 50 hour course, and the site is super easy to manage. They even let you retake tests a second time for a higher score.
In other words, impossible to fail this class, but of course it will look better if you get a good grade. And I'm sure getting any type of certificate will be ok, as long as you have something. I've noticed nowadays English schools are in demand for them.