My group has yet to level past the point of needing such a costly item, so I haven't had to deal with it. I am reluctant to put up too many barriers, but I might draw a line at that high of a cost being available in anything short of a major city.Just commenting here on 3 similar answers.
Is there a cost that is just too much? I can't think of a specific spell example but, 'diamonds worth 10,000gp' or 'an object from the Shadowfell'(for plane shift, for example) - can these just be acquired in any large town if the players have the resources to buy it?
I ask because that was the case for my wizard. My character had the money and could just, literally, buy anything. It felt weird. It's like those items had no story 'value' in the campaign. There was no story. They were just arbitrary numbers of GPs that you needed acquire. Meanwhile, in the same campaign, I played a Druid starting at 13th and made up a back-story as to why he had the spell component for a single casting of reincarnate. It wasn't, "he bought it in town", it was, "he did a favour for the local lake deity who gave him the rare incense to cast the spell." The DM didn't really care either way.
I'm not judging one way or another. I'm just curious how you handle what can be bought in a town.
The most costly component that's come up in the current series was for the Raise Dead spell, and they were in the largest city in the land, so I just said yes and the player paid the cost.