I keep an eye on the annual Barrett-Jackson classic car auction (starts this week) to gauge things. Values got pretty stupid just before the crash in 2008 https://www.barrett-jackson.com/
That seems like a great leading indicator. For a while I’d follow a few levels of real estate but the activity has seemed pretty strange and not very aligned to many other trends. I think the very large apartment companies using fancy stat models for pricing that update almost daily have moved interestingly too in both directions.