More than 1 in 10 U.S. adults is currently taking a GLP-1 weight-loss drug. And these medicines are getting cheaper seemingly by the day. Since Wegovy launched, its list price has fallen from roughly $1,300 per month to between $300 and $500 per month. Similarly, Zepbound was once about $1,000 per month, but it now costs about $350. The cash prices, for patients not paying with insurance, are even lower. These price drops are no accident. They’r…