Start finding information on the cost, use, etc. of your chemical.
Many of the encyclopedias listed have older editions. It can be helpful to check multiple additions because sometimes the information provided changes from edition to edition.
There are also many encyclopedias and handbooks online, which have the added benefit of being able to search the content.
Chemical prices can be tricky to find as there is no one comprehensive resource, since Chemical Market Reporter was bought by ICIS Chemical Business in 2006. There are multiple techniques to employee to try to find the price. What works for one chemical may not work for another.
SciFinder will usually provide information about companies that supply chemicals and sometimes will list prices. Once you determine which company produces the chemical, you may have to contact them to determine the price.
What is happening in the chemical industry that may be effecting your chemical, its feedstock, etc. (price, production quantity, etc.)? Searching business databases and trade publications can give you some insight.