If you apply to any job online, almost all of them ask you to have some sort of TEFL or TESOL degree. I realized that after I started applying, and decided to get my TEFL certificate. They're really expensive, so I just took one online, and that seemed to be enough. I think it is also gives you some help if you have never taught before.

Talk is that the PSB are asking for a Degree as well as a TESOL now, in Zhejiang province. I think the reason is that a lot of foreigners don't make the grade as a teacher. As Jnusb said, it does't hurt to do some sort of teaching course so you understand pedagogy, lesson planning and classroom management.

Just have a degree and some form of certification. Seriously. And don't pay for a fake one. When all of your students scores look like crap the school will likely get suspicious. You can find some online programs for 200USD at the cheapest.

I got a £300 TEFL for £65! I love you 'Groupon'!

Other than that I probably wouldn't have done it any time soon. At this present time if you've a university degree you can get a decent job.

The future may change though...

If you have your TEFL certification you'll probably make more than if you don't. These days, most places require you to be certified. There are some jobs that don't, however. I took a course online and every school I've worked at has accepted it so far. I think the really strict foreign run private schools might require you to have your certification from an in-class course. But there are plenty of other options.

Any thing to better your teaching methodology and creativity in class can't be a bad thing.