[inferiorhuman]

I'd start by looking at places that had huge real estate bubbles like Las Vegas or are far enough away from anything interesting (like all the shitty Bay Area suburbs).

For a lot of not great reasons I've a condo in one of those shitty Bay Area suburbs. Four units in this complex were listed for sale this year. Two sold for a bit under 500k, and two are still asking well over 500. So yeah I'd say the upper bound currently is $500k. Pre-COVID prices were in the low 400s.

I've checked out the property tax bills for my neighbors, and, yes, some have an assessed value of well over $500k. They've been underwater for about a decade.