I'm slightly out-of-date with TEFL, but I'm pretty sure that, as the others on here are saying, a CELTA is a far better investment than an online course. Apart from anything else, when you've just qualified with a CELTA you'll still be very green and there's a lot to learn if you want to do the...
Should add that increasingly countries are asking for a degree, too. In the old days you used to be able to fake them (I once had someone else's 3rd Class Degree in Librarian Studies from Manchester Poly, courtesy of Tippex and a photocopier - worked for years), I guess this is harder in a...
CELTA - either RSA or Trinity; the industry-standard basic qualification. RSA used to have bragging rights over Trinity, but don't know if that still holds.