I don't know if medical billing would be a good idea. It is very "boring" and exacting. I cannot keep at data entry like that for very long at once, it's not very satisfying or rewarding, can't be personalized and has no "I did this" pride aspects (nothing to "show" for your work). If I had to do it alone, without much outside stimulation (at-home, nothing to look at/see, no one to talk to, etc.) I would be truly crazy in under a day

I am in the middle of a data entry portion of a project I am doing for myself that I truly want to do and having a rough go of it and it is truly "mine" and words/about people not just some random codes on a form! I would do as Fresia suggests and find other medical billers and talk to them, where they work, how they like it, etc.

I think it is heavily advertised because the schooling makes money for the schools and organizations/associations but few who take the courses finish or become billers or get jobs or stay in the field. It's kind of like wanting to become a writer; lots and lots of people take courses and go to conventions, etc. but they never actually become a writer, they just like the idea of it but not putting in the time and doing the dirty work to actually become one. Look at how much it is advertised; if everyone could make good money by taking a course or two like that and work at home, etc. who would be working at Walmart? How many ads have you seen this week about becoming a doctor, lawyer, engineer, etc.? There has to be a catch in there somewhere?

If I had to do something from home, I would become an indexer: http://www.indexers.org.uk/index.php?id=164