Commodity prices can fluctuate daily, but benchmark information is out there! Price information for raw materials is mostly available but can be scattered across different sources. Assessments of those benchmarks and forecasts can be found through fee-based reporting services or through specialized industry publications. There are some government agencies and non-governmental organizations that do some of that work, but those reports frequently fall behind. Trade Associations can often provide information on supply & demand trends but rarely prices.
These are some starting points for different commodities categories.
The Price Reporters: a guide to PRAs and commodity benchmarks by