Assuming your numbers are accurate, I'm estimating your monthly "rent" or your contribution to the monthly expenses will be about $2,000.

This will help you get the most accurate estimates. 

This ensures you can provide them with a clear and accurate scope of work.

Hey @Joel Oh, So what the salesperson said could be accurate but for the fact that this is not for personal use.Tell me, would you want to get into a tub that had been used by 20-50 other people because they didn't change the water or do any real cleaning?

They should be able to determine the COC, annualized return, estimated ARV of a BRRRR, accurate rent comps and more.

Is there a more accurate way of assessing this? 

Underwriting a new construction is like a flip on steroids in terms of volume, however you will find that you can get a much more accurate budget in the end because unlike a flip, there are very few unknowns going into it.

Like websites or anything that gives accurate information. 

Quote from @Dave Schimmels: What is a good way to get accurate rent comps with existing tenants based on the area?

Connecting with local contractors or experienced investors in your area is also very helpful for getting accurate numbers.For ARV you’ll want to look at comps; You can start on Zillow or Realtor.com but I highly suggest connecting with a local agent.