Sound engineers make between $30000 and $80000 annually. This however greatly depends on the industry one works for, the experience and even the employer. For instance software publishing was the best paying in 2009.
2 Additional Answers
Starting sound engineers can make from $9 to $20 per hour. Salary increases dramatically with experience, and with 20 years of experience, hourly rate can be as high as $40.
There is no set salary for a sound engineer. It depends on where you are working. Some make millions, some make next to nothing. A sound engineer for Disney for example, will make a lot more then a guy that runs a small town recording studio.