Can Kit Prices be Negociated?

Sorry if this has been asked a hundred times before, but I'm new to this
group and didn't see it in existing messages.

I was wondering if most or all kit plane prices are fixed, or can they
be negociated like when purchasing a car?

As far as I can see, there are often special Show Prices for many of
them where either a discount is offered, or there are additional options
included in the base price.

Thanks,
Paul