Its about 1500 sqft and we are thinking of converting the smallest bedroom into a bathroom and making the den into the master bedroom.

You completely redo the bathroom in your unit for $10k.

Redo kitchen cabinets, bathroom fixtures, and vinyl plank throughout would put me in that realm but take a lot of investment.The property has several tenants that have been there for years and need new leases and rents raised.

I built a bedroom and a 1/2 bathroom down there because the upstairs only had 2 bedrooms. 

I would really like to get a rough estimate of what the following could cost.HVAC install for all unitsDig down basement and build out to make 1st floor an owners duplex down (2 bed, 1-2 bathroom depending on space, rec room)Adding laundry (stackable) in each unitI have had discussions with a realtor and one contractor, however curious in getting more opinions. 

What if the inspection reveals a non serious mold in the bathroom?

The house still needs to have a second bathroom installed (it has the plumbing) upstairs, and is probably worth $275-$300K as is.

Purchase price: $95,000 Cash invested: $95,000 3 bedrooms apartment two bathrooms to rent and know the market What made you interested in investing in this type of deal?

It sat in the middle of BOTH bathrooms.

The first floor has two bedrooms, one bathroom and includes the rear yard.