Regardless of what H1B visa holders are making, if you are a developer and are making less than $120k in the Bay Area, your employer is seriously ripping you off. If you're a good developer, and can prove that by your work, and communicate that across in an interview, you can quite easily make $150,000 or more in the Bay Area.
The U.S. Bureau of Labor Statistics collects data on how much people make in each area of the country, for various O⁕NET job titles/classifications. You can find out how much your peers make using this tool: http://data.bls.gov/oes/
I've uploaded a screenshot of how much software developers in the Bay Area earn: http://imgur.com/R8E1qdZ --it reveals that 90% of developers earn over ~$91k, 75% earn over ~$111k, 50% earn over ~$137k, and 25% over ~$166k, in the San Jose area.
The minimum wage for an H1B employee is based on O⁕NET job classification. If the person is classified under "Software Developers, Applications", they must be paid at least $98,342 in the San Jose area. My title at my company is "Software Engineer" and they classified me under "Software Developers, Applications" while applying for a visa for me.
Unfortunately, the O*NET job title classification system also has other redundant ones like "Computer Programmers" and "Web Developers". The prevailing wages for those are far lower. For example, in the San Jose area, the minimum wage for H1B "Computer Programmers" is ~$51k, and for "Web Developers" it's ~$66k. I can see how unethical companies would exploit that. To be honest, I'm puzzled where the Department of Labor got these prevailing wage numbers from. It almost seems like an error.