I have a 4 year college degree already and am interested in getting certified to teach English abroad.

Does getting this kind of certification require a large amount of hours at a university? Or is it a certification you can take a prep course and study prep books then take the test to obtain certification?

Thanks in advance for you help!

You have a few different options. There are several universities or language schools that offer a month long course, which is the route I would recommend. They generally consist of several hours of class each day and conclude with you teaching a practice class. The price range usually runs around one to two thousand dollars.
A second option is an intensive weekend course, which is much cheaper but does not cover as much material. This can usually be found at the same language institutes that offer month long courses.
Finally, an online course such as i-to-i can be completed at your own pace. It generally takes about two to three weeks for most people and is also quite cheap. It simply has the stigma of being online learning as opposed to a physical school.

Regardless of which option you choose, the materials are virtually always included as part of the program cost. Also, if you intend to teach in Asiaincluding China, Japan, Thailand, Taiwan or Koreacertification is not necessary, as you're qualified as a language instructor in those countries with only a B.A. or B.S.

Whatever you do get a proper qualification. A CELTA is the best introduction. CELTAs last 120-150 hours. Weekend courses are obviously cheaper, but what do you expect to learn in 20 hours? Online courses are rather like trying to learn to drive by correspondence - maybe not impossible but of very limited value.

In the last 20 years I have taught on EFL training courses of all kinds, ranging from 30 hours to 300 hours. Most short courses are of use only to try to hook people to sign up for longer ones - thus company benefits more than the prospective teacher.

If I sound like I'm on a crusade, well, I am - I am horrified at the way ELT is getting dumbed down. Teachers need to know a lot: language systems, language skills, learning psychology and materials management, and anyone straight off a CELTA is in my view an initiate, not a qualified teacher. So you can tell what my view on 20 hour weekends is.

There are countries where you can teach without any specific ELT qualification, but it is stressful, because you won't really know what you are doing, and dishonest, because you are like a lawyer practising without a license.

So find a course that will cover language systems (grammar, vocabulary, phonology, discourse) and language skills (listening, reading, speaking, writing) and one that provides plenty of work on lesson planning and plenty of observed teaching practice. Then you have a good grounding and can build on that.

TEFL courses in the USA, from a couple of weeks to six weeks to get your prep certificate, no credits.