Ending today, Gap cuts 30% off sitewide, including sale items, via coupon code "GAPFRIENDS". That's tied with our mention from three days ago as the best sitewide discount we've seen from Gap since early June. Shipping adds $7, or get free shipping on orders over $50. Sales tax is added where applicable and some exclusions apply.
A best bet is the Gap Men's 1969 Authentic Skinny Fit Jeans in Greenbow Wash (pictured) for $69.95 before the above coupon, $48.96 after. With free shipping, that's $21 off list and the lowest total price we could find. They're available in most regular and tall sizes from 28x28 to 38x34.