Mary Lou needed to buy a gift for her grandmother’s birthday. Her mother, Samantha suggested a new mystery book by good choice. Mary Lou checked the Internet to see who had recently released a book and read the reviews to see what she thought her Grandmother would like. When Mary Lou learned that her sister, Beth Ann was headed to the bookstore anyway, Mary Lou gave her the book title and enough money to pay for the book.  
 What purchasing roles were played in this scenario?