Dear PhilippS,
We try to keep the list of references that we use for SAM's default costs up to date on the
System Cost Data page
of the SAM website. Between the fluctuations of prices in the PV industry, the time it takes to analyze and publish cost data, and the fact that we release new versions of SAM with updated default cost values once or twice a year, those sources tend to be one or two years behind the current market.
The other sources listed on that page, like
NREL's OpenPV Project
and the commercial website SolarBuzz may have more current data.
Best regards,
Paul.