Ended up with about 5 acres and 1300 square foot house and 24x30 pole barn for about $27k. 

You then apportion your other building expenses and report those on the Schedule E as well.Here are the expenses you'll want to consider:Mortgage InterestProperty TaxInsuranceWater/Gas/Electric/Sewer/Garbage Removal/Lawn Maintenance/Pool Maintenance (presuming your tenant is allowed to use the lawn and pool)Repairs to the property as a whole (ie, roof, plumbing, electrical repairs)Repairs specifically to the space you are rentingDepreciationYou then measure the room you've rented and compare it to the livable square footage of the house.So let's say you're renting a 300 square foot space, your bedroom is 500 square feet and you share the kitchen, bathroom and living areas and those common areas add up to 1000 square feet.So your rented space is 300 + (1000/2) for an effective square footage of 800 square feet rented.You then take the above mentioned expenses and multiply each one by (800/1800) and you claim that amount of expense.The only exception is repairs specifically to the rented area.  

When I answered "Real Estate Investments", it raised a red flag, and it goes to the Legal Dept. for review.

While I know there are a nearly infinite number of variables, is there a range of per square foot costs to build?

Our property management company has just informed me that they will only charge the tenant to fix the square footage that was damaged (and this would be based on the age of the floors too -- home was built in 2001).  

Red flag #1. 

One example would be the parts of Wilkinsburg near Regent Square and Edgewood.

On the other end of the scale, C/D areas are 100% CF plays, since your exit strategies are essentially limited to other investors (who will always want to pay below-market) and those areas have almost no appreciation potential, but the increased vacancy, deferred maintenance, and Section 8 red tape mean the actual CF in those areas isn't anything like what you see on paper. 

The 2500 square foot plan I reviewed from caprecut was over $100,000.

The house was in poor condition, but did pass appraisal and qualify for a loan (after laying temp carpet and stick on vinyl squares myself one weekend and doing some painting on some facia boards...), and has good bones.  1 BD - 1 BA - 600 Sq ft.