I came across your decision after trying to check the legitimacy of a qualification awarded by TEFL International. As an employer, I can only advise people that Cambridge or Trinity are the only ways to go really. You are seriously limiting the places you can work and any career progression. If you are simply looking to go abroad for a year or two and teach to earn money to travel, then go ahead with any other qualification.

Don't think about the cost, just think about the doors it will open, or close in the case of most of these courses.