Adding living space to the basement- cost?

[Gina S.]

We are about to close on a 2 family home in Newton, MA. We are debating on renovating the basement to add additional living space for the first unit (2 bedroom and a full bath). This will require waterproofing the basement, moving some piping, adding a doorway, moving heating and water heater. We were hoping to add about ~600 sq ft. How much do you think it will cost? Is it worth it? Should save that money and buy a second house instead?