A lot of these old dears are a bit deaf , and don't always wear their aids around the house , I know what its like myself as I wear hearing aids, so its easy for them to miss hear the price.
I always write the price down on my survey sheet in large numbers ( no excuses re reading glasses ) and show them as well as TELLING THEM THE PRICE IN A SLOW AND LOUD VOICE , but not in a condescending way, and make sure they fully understand the cost, I also show them the survey sheet before I start the job and say something along the lines of "........ so if you remember Mrs Smith the price for this job is £xxx" saves any misunderstanding all round.