Estimating repair cost ...

[William Spencer]

Hey Everyone,
I am new at real estate investing and decided to start off wholesaling. I joined the local real estate investment club after reading a book I bought, and by now I feel pretty comfortable with the process. I met with a seller this morning (waiting on my offer) and I have 3 other appointments to walk through houses this weekend. My question is this:

In the book I read, the author recommended a formula for estimating the repair cost in order to arrive at the ARV. But I remember seeing somewhere during my research, a repair cost estimating tool ... I just can't find it again. Does anyone know where I can find one that's available online for free? The one I saw would allow me to refine my repair cost (be more specific) before I make my offer to the seller and I believe that can make a big difference in my negotiations. If not, please feel free to offer any practices that work for you. Please help.