All facets of professional writing tend to be underpaid for two main reasons: Most people that call themselves "writers" are by no means professional; and those that are don't know how to value their time properly.
So, how much does a content writer get paid? Anywhere from $0.001 to $2+ per word. Do yourself a big favour and don't sell your time and skills for anything less than US $0.10 per word. This should be the minimum wage in terms of professional writing, whether it is for a blog, a landing page or a brochure.
As your niche skills and job-hunting become better and better, that number can only go up. To date, according to PayScale, the average content writer gets paid nearly US $42,000 per year. That's about $160 per day, taking weekends off.
While content writing alone won't make you rich, it will pay the bills, buy groceries and allow for some household savings. For many of you, I know that the simple dream of a decent income for work at home ties in perfectly with this kind of career!
In terms of an hourly wage, I suggest starting at a minimum of US $10 and moving up as you become more confident in the work. (For comparison, I currently charge $30 per hour. With some practice and fine-tuning, you can get there too!)