One way to analyze the effectiveness of your cost management is to use the Most Used Items Report. This report will show you a list of your top 25 most used items, and includes a link to run a Usage Report for each item. Use this data to determine if there are potentially alternative products available that you could consider using to manage expenses down for your most frequently used items.
This report automatically defaults to the last 30 days, but you can click on that box as there are a number of other date range options available. You can also sort by column header by clicking on the title of each column.