I need to run 325 feet from a transformer to a 200 amp home. What gage do I need. I estimate 250 mmca copper, but want some assurance. The power company wants $7,500 to move a transformer closer (not going to happen).

Not enough information...
What is the voltage and phase?

Nowadays 33kV ABC cable is available,lay it by erecting a couple of GI pipes from Utility pole to your house if it is cheaper than USD7,500.

Interesting... this is a simple voltage drop question which can be answered with any one of a few dozen of calculators available for free...
I expected something more but... only silence