I dont remember who discusses this….
In the context of the nedavos brought for the mishkan, the torah mentions zahav, kesef and nechoshes. Clearly items listed in descending order of value. After these three, the torah mentions the avnei shoham. Certainly these stones were more valuable than at least nechoshes (possibly the kesef and even zahav – diamonds are girls best friend, after all), yet are mentioned last. I dont remember who says this…the reason the avnei shoham are mentioned last is because they yidden collected these as they fell from the sky every day with the man. Since they didnt spend any of their own money on it, the torah is not machshiv it.
Still reviewing hilchos chanuksh, but I remember from last year seeing one of the nosei keilim discuss the quesiton if it is more mehudar to use a beautiful but not so expensive menorah, or an expensive, but not so nice looking one. I believe the answer given was the hiddur was determined by the money spent, not necessarily the appearance.
To answer your question. I would say that using an expensive kos to make kiddush would qualify as hiddur. Of course, I have to get “chapter and verse”, until then take it as you want.