1/2 Bath to 3/4 Bath Conversion

[Isaac Dylan Lane]

I am getting a half bath converted into a 3/4 bath in my house. Once the work is done, I will be renting that room. My house is a 3 Bd, 1.5 Bath and was built in 1948. 1400 Sq Feet. It has a concrete slab foundation. The standing shower will need to be custom built. I had a contractor, and a plumber come to look at the room, and their quote on the work was $9600, not including materials. The .5 bath is a small space, but is manageable by making a corner vanity, and by making the door swing in the other direction. 

This seems a bit high to me, but it would be the first time that I paid for this type of work. Can anyone share their thoughts or experiences with this situation in terms of Return on Investment?