Calculating Arv/repair cost

[Ligmon Williams]

Hey guys have A few questions that I think could help me and many other wholesalers/real estate investors close more deals.

1. What tools do you use to accurately calculate the ARV of a property?

For ex. I use propstream and Zillow if their are properties that has sold for 175k, 132k, 115k and 120k all fixed up do I get the average of these 4 numbers or can I go with the highest number ?

2. Also, if I'm looking to get the arv of a 3/1.5 but only 3/1 and 3/2 have been sold in the area how do I go about finding the ARV of the 3/1.5 ?

3. I was told by a GC out of NC that to estimate cost of repairs in a property you would consider a light rehab you could get the sqft of a property and multiply by $25, medium $35, heavy $55 and full rehab $75+. I know this definitely works in his market but Do you think those numbers would be the same or close to the same everywhere else ?