Anyone charging less than $100/hr is probably underselling themselves. The only time you should charge less than that is on very long term contracts with hundreds or thousands of hours, and then, only hesitantly. People make assumptions based on what you charge - frankly, I've found that people tended to blow me off when I charged much less than this, and actually listen when they know they're paying a decent amount…
When we link freelancing rates with salaries, we can easily get led astray by: "OMG $200 an hour — that's like $400k a year full-time! That's insane!" If you're looking to augment staff as a contractor, whoever hires you is going to want to compare your hourly rate with what they're paying their team — so it's going to be tricky to break through that ceiling. But if you're working with clients who have problems to so…
"Yeah, think of the break you're getting - where else could you buy a 400k/year caliber employee for the handful of hours you need them? It's a great bargain!"