To get the same numbers for the LT rental, I'm estimating the rents would need to be at least $2,800/mo.

Now this property is in a class C neighborhood with a calculated 11% cap rate estimated.

you just have to estimate them based on what the property needs.so if it needs a new furnace + a bathroom gut and remodel + new windows, you estimate that.  

Hopefully, based on actual field measurements, past project data, and estimating software, your contractor can develop a detailed estimate that lays out the cost of labor and all materials for each phase of the project.

Modeling uses templates to estimate allocations although some firms still dig very deep on these types of studies, costing $1,000–$1,250.DIY tools are cheaper but often miss deductions and lack audit-ready documentation.

When in Due Diligence have a thorough inspection and get estimates for any work that is needed now and potentially in the next 3-5 years. don't forget about the tax benefits to doing the work upfront.

These methods include:Detailed Engineering Cost ApproachDetailed Engineering Cost Estimate ApproachSurvey or Letter ApproachResidual Estimation ApproachSampling or Modeling ApproachExperience or “Rule of Thumb” ApproachFor further details on the methodologies, refer here.WHAT ARE THE BEST AND WORST PROPERTIES FOR COST SEGREGATION STUDIES?

Not only is their cashflow estimate fake, but it's unsellable with the surprise cap ex or tax increase.

After a bit of back-and-forth on the repair costs, I negotiated it down to $69,000, convincing them the extent of repairs was higher than they initially estimated.

After a bit of back-and-forth on the repair costs, I negotiated it down to $69,000, convincing them the extent of repairs was higher than they initially estimated.