We are going with the RE agent report - before and after.  Will be some 100s of bucks, but it is worth it.

Lift, ramp, handles were the biggest improvements.

The medical improvements make it less attractive for the general population of homebuyer such as families.

A RE tax assessment generally correlates, or tracks, the fair value sale price and could be viewed as a proxy for an actual agent report. I don't think that argument would win but lacking any other evidence, it could.

Thanks to you and everyone else who replied.