Most purchases begin online. For example, a consumer searches for "discount Viagra" and clicks on a link offering low-cost versions. At a traditional pharmacy, Viagra sells for $15 or so a tablet. Fakes online cost as little as $1 per. The e-retailers, sometimes called "affiliate sites," are often designed to suggest a bustling operation based on a real clinic. When a consumer places an order on an affiliate site, he's handed off to a "core site," which pays the marketers for referrals. A core site may work with hundreds of affiliates. To fill an order, the core operator turns to a network of suppliers. Most of these are based in India and China, often alongside the factories making legitimate drugs.
