School/travel backpack with USB port for $14.85 (with promo code) on Amazon. Great reviews!

Amazon has got this school/travel backpack with a USB charging port priced at $32.99, but enter promo code 55A3TPN1 at checkout and that price drops by 55% to $14.85 with free Prime shipping.

These backpacks got 4.2 out of 5 stars over 48 customer reviews.

Comes in gray, blue or black.  Has a USB charging port (you need to provide the portable charger) and earphone holes.