Sierra Trading Post offers the Dickies Men's Regular Fit 5-Pocket Bootcut Jeans in Black for $9 plus $5.95 for shipping. That's the lowest total price we could find by $8. They're available in waist sizes 32 to 44 and inseams 30 to 36, although not in all waist/inseam combinations.
Walmart offers this Dickies Varsity Backpack in eight colors (Black & White pictured) for $7.50. Opt for in-store pickup to dodge the $5.99 shipping charge. That's $11 off list and the lowest price we could find.