On April 3rd, 2015 EPA published the 2014 and 2015 Cellulosic Waiver Credit Prices. Read the EPA's Direct Final Rulemaking here.
The EPA also published a guidance paper on the cellulosic biofuel standard which intends to clarify obligated parties options for compliance as well as the price calculation formula of cellulosic wavier credits. Read the Cellulosic Biofuel Standard Guidance here.
Additional information regarding renewable fuels regulations and standards can be found on the EPA's website here.