Buying first Duplex!

[Brett Riemensnider]

I’m looking to buy my first duplex here this week hopefully but am struggling to find the numbers I need. I’m not sure if I’m just second guessing myself but I feel that this is too good to be true. For the vets here, are there any good links to help with confirming my numbers are correct. Rental income, closing costs, rehab costs? I tried to use the BP calculator but even then I’m having a hard time knowing what the property is actually worth, or what it will  cost to put the work that needs to be done in it before renters move in. I feel like maybe I’m just getting cold feet and don’t want to sleep on a good investment. But also don’t want to shoot myself in the foot by buying a bad one! Any advice or links to sites that you use for your due diligence would be greatly appreciated! Thanks!