While it's true that the bid-for-work sites are uniformly awful, there is one organization that acts just like a broker: Toptal. It's not for those just starting out as they only take on people with significant career experience and skills, and one must pass through a rigorous screening process. But after that, one sets one's own rate (anywhere between $50 to $200 per hour) and all the jobs listed have come directly into Toptal via its client liaison team. Some of these jobs last a few weeks, some are extended by the client for years. There is no application fee, no hidden costs, and everything is above-board. I originally learned of this company through reading an article here on Medium, and am very happy that serendipity occurred.