1/2 bath to full bath conversion

[Sam Dal]

Guys - I live in a $1m NYC borough that currently has 3 bedrooms on the 2nd floor with 2 bathrooms. The basement has a full bath while the 1st floor has a 1/2 bath. I have to this 1/2 bath to a full bath conversion to accommodate a senior family me who cannot climb stairs anymore. I've gotten rough estimates between 30-40k to do this (breaking down internal wall, plumbing, electrical, everything that's required). Where would you folks place a return on investment going from an older 1/2 bath to a new full bath? The end result would be a home with 3 bedrooms and 4 bathrooms. If the answer is favorable, I'll do this but if not, I'll probably have to do a stairlift that I know rarely adds any value

Thx