50-60% of my revenue is sub-contracting. I have a few firms that often take on projects that they are not suited for or do not want to increase staff to cover and they often sub out all or parts of the project to me. These relationships were built through networking with other developers who worked for these companies - never the bosses per se. Meet other devs and when the company needs help, they remember and recommend. In my experience this kind of introduction is about 5x as fertile as a cold intro.
Roughly 30% of my revenue is from direct relationships between myself and another company. These tend to merit a higher rate but also increased risk.
Very few of my direct relationships start from cold calling/intro (not sure if any ever did actually); most came via word of mouth recommendations of other people. Networking at the right kinds of events can also increase your profile and help you meet the right people.
ProTip: Networking at networking events is a terrible idea.
Lacking a sales force the best pseudo sales force you can create are acquaintances who understand your skill set and respect you as a person. They don't need to see your work, they don't need to have hired you before - to drop your name to someone who asks. They need to know your name, what you do and have a generally good feeling about you. If you pay them back for this, even with a simple thank you or lunch - they will continue to be an advocate for you.
Another tip which probably falls into the anecdotal evidence category - get off of ODesk and ELance. You are right about the price war. Your name and value to people also gets damaged because you seem to be just another guy among thousands who need to find work that way - it is a 'dime a dozen' mentality and they will always see you as that.