Estimated cost to convert half bath to full?

[Daniel Pitta]

I'm trying to get some kind of ballpark figure for what it would cost to convert a half bath to a full. I have a friend that is looking to move out of their 3BR/2.5 bath home in Rockville in the next year. The basement is livable and has a half bath; my thought is that if I can convert it to a full, I'd be able to pocket more in renting out the space. The upstairs has a master bedroom with full bath attached, another full bathroom across the hall, and two bedrooms; one they have been using as a study, and the other as a guest bedroom. 

Looking at the basement as a rentable space, the house is 4BR/2.5 bath. They're located in Rockville, off of Aspen Hill & Veirs Mill. I was told by a friend that's a RE agent that this area of Rockville doesn't offer much in terms of appreciation, but I'm trying to figure out if it could be a potential house hack. I'll be there Sunday to get more info re: what price range they're looking to list it for. The one caveat is that they have a large inground pool in the backyard which seems like a huge sunken cost. I would want to remove the pool if I ended up buying the property, but have no idea what that would cost.