Possible Clues:

• Engage in retail therapy?
• Get many price quotes
• Betray beginnings of Stanley's History of Philosophy
• Visit Saks, say
• Inform against
• Observe Black Friday (and a chunk of the eight longest answers)
• Visit Amazon.com, say
• Make comparisons at the mall, say
• Betray mum and ring head of police
• Visit an e-mall