Adding a bathroom and renting by the Room

[Chris Renzi]

Hi BP, Two questions here: 1. Spend the money to add a bathroom now. 2. Renting by the room or as a 5bd. 

I'm currently in a house hacked duplex in Somerville, MA. Bottom unit is rented as a 2bd 1ba. I am renovating the my unit, (4bd, 1ba, but has two offices that can become bedrooms. 1 would need a closet or armoire, other needs hallway access, which would come with the new bathroom)  paint, floors kitchen, looking into adding a bathroom but i'm getting quotes in the $50-60K range which seems extremely high? If I added the bath this does open up a hallway to the additional bedroom making it a 6bd 2ba. My goal is to get minimum $5K /mo. for the top unit, which I think I can do without adding the bathroom but could get in the $6K+ range with additional bath. Longer term plan is to condo out the duplex. 

Do I invest in the bathroom now or use capital for another investment? And do folks have experience with renting by the room? If so, what are the pro's and cons? 

Thanks!