Rehab rules of thumb

[Derrick McCrary]

Can anyone weight in on a ball park of what the following are costing flippers in the Atlanta area.

The numbers don't have to be exact, just in range to tell if the contractor is attempting arm robbery without a gun.

all advice and info welcomed.

Hvac 

Roofing per square

Pluming per square foot

electric per square foot

dry wall

I say again; nothing point on.  Just something to gauge if the contractor is robbing.