A medical transcriptionist can earn good money, as an independent contractor, working for a service or working directly for a doctor.
Many medical transcriptionists are paid on production; that is, you will earn a set rate for every line you type. For example, when I started out in medical transcription, I was paid $0.065/65 character line.
This means that you can earn more if you improve your skills. In my experience, improving my transcription skills had two benefits: first that I earned more simply due to speed, but second that I was able to get a pay raise so that I earned more than the beginning rate.
According to the Department of Labor, the median salary for a medical transcriptionist is $15.41 as of this writing.
Some medical transcriptionists earn hourly pay instead. This is more common for transcriptionists working in offices than at home, as paying on production assures the employer that they are only paying for productive time.