Two recent salary surveys have shown that R language skills attract median salaries in excess of $110,000 in the United States.
In the 2014 Dice Tech Salary Survey of over 17,000 technology professionals, the highest-paid IT skill was R programming. While big-data skills in general featured strongly in the top tier, having R at the top of the list reflects the strong demand for skills to make sense of, and extract value from big data.
Similarly, the recent O'Reilly Data Scientist Survey also found R skills amongst those that pay in the $110,000-$125,000 range (albeit amongst a much smaller and specialized sample of respondents).
The reports also show that IT wages in general are rising at around 3% per year, largely due to increased demand. You can download the full reports at the links below.
O'Reilly Media: 2013 Data Science Salary Survey