Several companies have emerged to capitalize on consumer anger over the confusing variations in price. The players include not only Blink Health and its better-known competitor GoodRx, but also veteran businesses like the benefit manager Express Scripts, which recently helped to start a subsidiary aimed at cash-paying consumers. Amazon, the online behemoth, is also said to be considering whether to join the fray.

Last Sunday, CVS Health announced plans to merge with health insurer Aetna, a move that would create a corporate behemoth that many have said would have little incentive to serve the needs of regular people. Some consumers say their experience with CVS already demonstrates how easy it is to fall through the cracks. In one case, a customer whose plan was managed by CVS Caremark, the drug benefit manager, would have had to pay more for a drug through her plan at a CVS than what she ended up paying at the same store, with a coupon from GoodRx.

Representatives for insurers and pharmacy benefit managers say cases like Mr. Swanljung’s are “outliers.” “There are three to four billion generic scripts written a year, and in the vast majority of cases, they are going to get a better deal by using insurance,” said Mark Merritt, chief executive of the Pharmaceutical Care Management Association, which represents benefit managers.

A spokesman for UnitedHealthcare, Mr. Swanljung’s insurer, noted that while Mr. Swanljung got a lower price for generic Crestor through Blink Health, he also takes four other prescriptions, for which he got a better deal by using his insurance. (Mr. Swanljung gave UnitedHealthcare permission to discuss his situation.) Having insurance is clearly valuable, said the spokesman, Matt Burns. In addition, the co-payment for generic Crestor, also called rosuvastatin, in Mr. Swanljung’s plan is set to decrease significantly in January, in large part because the price of the drug has dropped this year.

Consumers also may face penalties if they don’t use their insurance and pay cash to save money. In many cases, insurers won’t let them apply those purchases to a deductible or out-of-pocket spending maximum.

Still, many find that leaving their prescription card at home is worth it. Some have found a better deal even at pharmacies that are owned by their drug plan, like CVS.