To restrict values in a drop-down in a Price Parameter key column based on another Price Parameter column:

1. Open a Price Parameter table and right click the column you want to use as a source.
2. Click "Add Columns to 'Rename.../Restrict Values' List".
   
3. Go to the column you want to restrict and click 'Rename and Customize Column'.
4. In the 'Restrict Values' drop-down select "by Data Source".
   
5. Click the add button "Select a Data Source Field" and in the popup window select the Data Source you marked as the source column.
6. Select the field you want from the Fields picker and click the Select icon. 
7. Refresh the Price Parameter table to see the effect.

This applies only to the matrix tables.