ICIS Chemical Business
This trade magazine includes reports on individual chemicals, including pricing for a specified geographic region, at the back of every issue. The July 19th 2019 issue has many of their Chemical Profiles compiled in that special issue. Normally only a couple chemicals and regions are included per issue, so it sometimes takes some digging to find exactly the chemical you want. Searching for your chemical's name AND (price OR pricing) can help, but you may still need to convert currencies and estimate based on pricing outside the United States. Access via ProQuest includes pdfs of the pages, including graphs, while graphs are not included in the EBSCOhost version.