RanDigits-US via Amazon offers this Men's Leather Reversible Belt in Black/Brown for $10.99. Coupon code "CI7I9IM6" cuts that to $4.99. Plus, Prime members bag free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $5.48.) That's about $5 under what you'd pay for a similar belt in local retail stores and the lowest total price we've seen for any men's leather reversible belt. It's available in sizes 35-36 to 45-46.
A close price: Styleosity via eBay offers a similar belt with prices starting at $5.19 with free shipping. (Prices vary by size.)