Keep hammering the point that they are cheaper. If they are open to more advanced discussion point to the amazing structural changes that batteries are only starting to bring. Tell them something that sounds mildly like science fiction but is in fact happening already and will be HUGE. E.g. the battery you’ll have in your AC/stove/car will save you money or even make you money when part of a smart mesh of DERs.
Maybe I’m too optimistic :)