Amazon offers Prime members the ExOfficio Men's Give-N-Go Briefs in Black for $11.30 with free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $5.58.) That's about a buck less than you'd pay for any color in local stores. They're available in select sizes from S to XXL.
Note: Sizes M and L will be in stock on September 11 but are orderable now at the above price. Also, they're available in Stop (S only) for $10.66 with free shipping for Prime members.