You will also have cleaning supplies, legal / accounting fees, and if in your area possibly AC maintenance.

Do you usually supply trash cans?

Still one of the lowest ranking cities for supply delivery.

Especially on the farm when I need to cut some metal away from a power supply which is 80% of the time.

Go to Home Depot and Lowes and ACE and hang out in the building supplies section, those generally are people who are contractors who know rehabbers or are rehabbers themselves.

You can do a square footage estimate - but that is only an estimate, and probably not a very accurate one until you've got a bunch of experience under your belt.You can line item all the "stuff" - this takes a very long time when you're getting started, and it's probably not very accurate either, especially when you are pricing at the HD, but a lot materials are going to come from a contractors supply (if using licensed contractors), and labor rates vary greatly.You can try to get a GC to come out and give you an idea of cost - but be aware that GC's don't like this, especially when they show up and find "another cheapskate investor trying to slap lipstick on a pig". 

I also pay less for electric, water, sewer, gas and supplies. 

I hope your MIL sees your side of the argument because I've seen things go very wrong as 2 year timelines tend to double,,, especially if you make a mistake with drawings/permitting.Another issue is there is a surplus of rental supply currently and rents have been steadily coming down in JC/Hoboken last 6 months or so.Best of luck! 

Had a couple years in between Moto shops that I worked for Western Nevada Supply, and that really opened my eyes to real estate.

Total costs about 150 bucks in supplies with plenty left over for future treatments.