Finding Chemical Prices is a challenge. If you are looking to actually buy a chemical and need a price, you really need to go through the producer.
It is possible but very difficult to find current bulk pricing. Foster Business Library's Home page provides quick links to some tools which can be useful, including EBSCO Business Source Complete (below). Try searching by the chemical name and the keyword `prices'. Keep in mind that these are business databases and not chemical databases. Be sure to try chemical synonyms if you don't succeed on the first search and be careful with initialisms and abbreviations. The librarians at Foster can be of assistance in using this database and may be able to recommend further sources.
There are many resources for finding historical prices of many chemicals. Encyclopedias like Kirk-Othmer and many journals provide excellent coverage.