How much should I charge this lady for web development?

This lady has these designs that she needs to be coded into 20 web pages. The navigation is pretty much the same so really it's just different text and pics on the rest of the pages. Her budget is a little tight and that's why she designed it herself. I'm not sure how much I should charge. I don't want to scare her away. I have four years of working experience and my last position was around 20ish an hour.