It goes both ways on this. Sometimes it costs nothing much above the co-pay (if that), other times, orders of magnitude.
It doesn’t hurt to ask. It also doesn’t hurt to try to stock up on prescription meds, as about 90% of the Americans taking drugs on a regular basis are about to learn, as China’s exports begin to shut down.
One would think that the pharmacies’ checkout system would automatically inform the customer of their best price. Why bill through insurance if it will cost the customer 5 times more than the cash price?
I take low-dose aspirin. It is not that expensive either way, but it is a lot cheaper to buy it off the shelf than to get it filled. Sometimes can get buy one get one free. And the insurance will only do 30 at a time whereas I can get 90 count on the shelf.