I think the dismissals come because wheelchair users are already painfully aware of the options.

Yes, there are different kinds of wheelchairs, there's no reason a premade, presized wheelchair has to cost thousands and they don't. The premade chairs certainly serve a need - for those who can sort of walk but need the chair to go distances (etc).

But the reason for custom wheelchairs is they are for people who spend all day, everyday in the chair. And that's where the need and the pain is greatest and so exhibiting a "ready made" chair just isn't going to impress them.