Assisted-living centers have become an appealing retirement option for hundreds of thousands of boomers who can no longer live independently, promising a cheerful alternative to the institutional feel of a nursing home.

But their cost is so crushingly high that most Americans can’t afford them.

These highly profitable facilities often charge $5,000 a month or more and then layer on extra fees at every step. Residents’ bills and price lists from a dozen facilities offer a glimpse of the charges: $12 for a blood pressure check; $50 per injection (more for insulin); $93 a month to order medications from a pharmacy not used by the facility; $315 a month for daily help with an inhaler.

The facilities charge extra to help residents get to the shower, bathroom or dining room; to deliver meals to their rooms; to have staff check-ins for daily “reassurance” or simply to remind residents when it’s time to eat or take their medication. Some even charge for routine billing to a resident’s insurance for care.

“They say, ‘Your mother forgot one time to take her medications and so now you’ve got to add this on and we’re billing you for it,’” said Lori Smetanka, executive director of the National Consumer Voice for Quality Long-Term Care, a nonprofit.