This is largely opinion based, and also based on your experience, skill and clients. It's incredibly hard to price yourself when you start off, but the only real way is to pick a start point and work with trial and error until you get to a rate that matches your quality (and efficiency, if working hourly).
I'd consult this article. It's extremely valuable information:
Some relevant useful snippets:
I started out my pricing like most freelancers. I charged an hourly rate for the time that I worked. A client would come to me and I would either estimate the number of hours that a project would take.
Over time, I kept raising my rate from $30 to $50, $60 and higher. At $60 per hour, I was beginning to start working with higher quality clients who had decent budgets.
A client came to me via oDesk at my $60 per hour rate. I finished the website in 3 hours… And worst of all, the website looked freaking good. I had just created a high quality website for this individual, and I had only been paid $180 for it.
They seem to suggest starting out hourly and building up to a point where you charge for the whole project. It's ultimately up to you.