Given the property assessment shenanigans that go on in Cook County and it's neighbors, this valuation is probably right in line with it's taxes.

This.

I've been looking for places in Portland and find the Refin estimation uncannily close to a 1:1 correlation with property taxes, unlike, say Zillow which is more optimistic.

I understand that this is to be expected, but its really sort of unbelievable how tight the correspondence is.

That’s a great deal, although so is the White House—only $21 million! (https://www.redfin.com/DC/Washington/1600-Pennsylvania-Ave-N...)

Zillow has it at around $400 million, which seems at least closer (although probably still too low.)

Hmm...I bet the owners beg to do differ with the valuation.