"It's one of the dirty secrets of the pharmacy industry that uninsured people frequently pay more for drugs than those with insurance, [said Adam Fein, president of Pembroke Consulting]. That's because the prescription drug plans can use their clout and scale to negotiate lower reimbursement rates with the pharmacies, while uninsured people pay more.... '[Wal-Mart has] many more cash-paying customers than the average pharmacies, and as those people got insurance, the insurance companies decided in some cases they would pay less than what Wal-Mart was getting from the cash-paying customers,' Fein said."