How to estimate rehab costs in a pinch?

[Christina P.]

I am a newbie looking to purchase first LTR in student housing neighborhood around University hospital.  In researching the area, I discovered another area investor is rehabbing his purchased properties to convert living spaces (ie dining rooms) into additional bedrooms and also adding en-suite bathrooms to new and existing bedrooms, thus increasing occupancy and cash flow.  He rents out by the room.

In the current market, these houses are selling in a few days.  I am finding it difficult to analyze the properties without knowing what the rehab cost would be.  What is the best way to go about this?  Do I find a contractor to put on standby?  Available time once property is listed to get in there, with contractor, get estimates (especially more than 1) and then analyze #s seems very limited and tricky.