Kohl's offers the Levi's Men's 501 Original Fit Jeans in Black for $17.85 plus $8.95 for shipping. Outside of the mention below, that's the lowest total price we could find by $8, although we saw them for $4 less in May. They're available in select sizes from 30x34 to 46x30.
A close price: Levi's offers them in David for $20.34 after coupon code "40SUMMER", plus $7.50 for shipping. Select sale colors are slightly less after coupon, although sizes are extremely limited.