Don't spend too much on a teacher training course. Getting a TEFL or ESL certificate is just icing on the cake.
When an employer sees your resume, they wont necessarily have in-depth knowledge of all TESL courses offered around the world. Hence, they generally wont know whether
TESL Course A is better than
TESL course B. They will only look at the fact you have a TESL Certificate.
Schools are in the business of getting students and making profits, not examining the range of TESL courses on offer. As long as you stick with a reputable company, then all is fine. An employer will see a TESL course as have 3 levels of quality:
- Online
- Weekend
- Few weeks
So, if you get a TESL certificate that is online, then obviously it will have less weight and importance than a TESL certificate done over a few weeks.
As you already have a post-graduate degree, don't spend too much money on further training. An online TESL course should be fine for you. And stick with the well known TESL providers.