While folks (particular Jason) are giving you excellent advice, can I take this from another angle? A $20 bill rate does not mean you are getting $20 per hour. Not even close. You have to factor in all the non-billable parts of consulting, like writing proposals, educating these clients that $10/hr providers will likely not lead to project success, and handholding them through the project because they'll likely need lots of it. They're disproportionately likely to be pathological clients because they are attempting to do business in a place which might as well be marketforlemons.com to save a few hundred bucks. It took me years to adjust to this, but it is true:
a few hundred bucks is not a lot of money.
Can I strongly suggest you make a small investment in improving your business skills, get clients in the old- or new-fashioned ways without a marketplace site, and laugh in the general direction of a $20 bill rate? Also, don't call yourself a freelance programmer. You solve problems for businesses. Many businesses have problems such that there is no number they will not pay to get them resolved.