Doing this in PrintShop Web, would require maintenance of the drop down list and custom jqueries - not an easy or time-saving task.
I would recommend this user keeps an Excel file with all the contact persons. One of the rows can be the amount of business cards that need to be ordered for each person (ie that month).
Those in need of business cards will inform this person, and the Excel sheet is updated with the requested amount of cards. The PrintShop Mail template will be set up to use number of copies of the layouts linked to the field with the amount of businesscards for each person (skip entirely if 0)
Periodically, the Excel sheet is uploaded to PSW, where the job will be generated all at once. After this, the client will reset all amounts in the excel sheet to 0, after which everyone can file their requests again to be put in the Excel sheet, and so on.