Staples offers the Jansport Vector Accessory Pouch in Black for $6.39. Opt for in-store pickup to avoid the $9.95 shipping charge. That's the lowest price we could find by $10. It measures 3" x 7.5" x 2.5".
Marmot offers its Marmot Men's Crux Shorts in Team Red, Black, or Bright Lichen for $20.97 with free shipping. That's the lowest total price we could find by $16. They're available in sizes L to XXL, although not in all color/size combinations.