Stephen Bosch and Kittie Henderson have published "The Winds of Change: Periodicals Price Survey 2013" in Library Journal.
Here's an excerpt:
This year, the serials pricing data indicates that prices are increasing at about the same rate as last year. Increases seemed to have plateaued at about 6% for 2013. Data from the merged ISI indexes shows a 6% increase for 2013, unchanged from 2012. EBSCO's MasterFILE Premier and Academic Search Premier show similar results: average prices for titles in MSP increased 5% for 2013, while average prices for titles in ASP increased 6% in 2013, the same increase as for 2012. The Consumer Price Index (CPI), on the other hand, advanced 1.7% for 2012, which means serials inflation continues to far exceed general inflationary pressures and library budget adjustments.