I’ll also amortize large items like roof over 20 yrs, and then add $100/mo/unit for general repairs.

Here's a https://www.irs.gov/businesses/cost-segregation-audit-technique-guide-chapter-4-principal-elements-of-a-quality-cost-segregation-study-and-report to the IRS website noting specific items that are included in the cost segregation study report. hmm, that website is a 404 error.  

After adding those four items back in, it brings the complex to making around $6,500.

One your loans will be a higher interest rate, next you will have annual filings, the cost of a registered agent every year, and items like that. 

It is not your responsibility to house this person's items indefinitely in your rental. 

This will give you one critical piece of information, that it may take X days to get an offer and sell, and the second item will give you what your competition is right now.

The other business I run is reselling, listing items on eBay & FB.

What were the biggest line items?

There are a lot of options out there.Some of the most useful items BiggerPockets members have identified are features that save time so they can spend time working on their next property.

The contractor I hired finished the Foundation work in 4 weeks and tenant started reporting damages, thefts to items in Garage which contractor denied.