Is there a way to have a data driven loop iterate X number of times where X is a variable value?

I have a web test with a DDLoop.  This test basically simulates ordering items.  My dataset has thousands of items from various departments.  I created a user form that allows the user to select the department that houses the items they want to order.  I am trying to give the user the ability to tell the DDL how many items to order - how many times the loop should iterate.  The DDL create wizard gives the option to set this at time of creation, but I can't seem to figure out how to make the End Record value a variable value. 

Any thoughts?

Thanks for your time!