In terms of technology skills, PHP is definitely at the low-end in terms of what you can get on an hourly basis... http://tinyurl.com/lxsxp3n

To make you more marketable to potential clients, I'd recommend focusing on some skills that are complimentary to programming. That may include domain-specific knowledge of a particular type of client you want to work with (e.g. bioscience, healthcare, local government) or it may include things like usability, SEO, or lead-generation. Find the profit centers in your clients business and find a way to get as close to those as possible. Learn the language they use to describe their work and make sure you use the same vocabulary when speaking with them.