Saks Fifth Avenue offers its Saks Fifth Avenue Collection Men's Logo Briefs 2-Pack in Black or Grey for $6.75. With free shipping via coupon code "FREESHIP", that's $16 off list and the lowest total price we could find. They're available in most sizes 30 to 40, although not in all color/size combinations.
Saks Fifth Avenue takes up to 70% off select men's and women's items during its Fashion Flash Sale. Plus, score free shipping on all orders via coupon code "FREESHIP". Note that sizes may be limited. A couple best bets: