Because you will have more kitchens and bathrooms with a duplex vs SFH you should experience increase maintenance cost.  

The sellers marked it down almost $150K.The house looks solid & has curb appeal plus I can rent out the 3 upstairs rooms & my roommates have their own bathroom to use, and I have mine in the basement.

The house was listed as a 2 bedroom 2 bathroom but was disclosed on the MLS listing that the 2nd bathroom was extended but was done so without permits.

Assuming when you say "full gut" that you mean new plumbing/bathroom(s)/kitchen, the $30k with materials quote is essentially impossible--materials alone would probably be approaching that number.

. $240k per year in short-term rents, as an 8-bedroom, 4-bathroom mid-century modern home with a large pool located on a golf course.

So far just planning minor bathroom and kitchen upgrades - flooring, appliances, cabinets - but long-term there is potential to convert these large units to condos and sell.

The majority of our SOW included: cleanup, new roof, exterior siding and paint, flooring, interior paint, ceiling re-texturing, cabinet refinishing, counter tops, light fixtures, windows, doors, bathroom gut, and landscaping.

Do these bathrooms have showers?

Purchase price: $25,000 Cash invested: $15,000 Sale price: $50,000 5 bedroom, 1 bathroom, 1,872 sq ft house that was purchased in distressed condition.

That being said, I personally wouldn't install in a bathroom.