How to create a chart for tracking Product stock over some period of time using Ubercart?
You should try views charts for creating graph 


  About the Project
  
  Provides a "charts" style output for Views module so you can render
  result-set not just as text (list, tabular) but as pie-chart,
  bar-chart, scatter-plot etc.
  
  DC DrupalCon '09 Presentation
  
  http://vimeo.com/5306364
  
  Dependencies
  
  Views Charts and Graphs Suggested modules
  
  For Drupal 6 you will need the Views GroupBy: if you want to chart
  anything actually useful. Views 3 for Drupal 7 has grouping built in.
  Documentation
  
  Views Charts has basic usage instructions available as Advanced Help
  pages. Please install and enable it to see the available help.