I am trying to estimate how much a red is making by monitoring alignment change. Just playing around I have a rough guess of 625 credits per -1 alignment. Does anyone have a more informed figure? Does the type of cashing (SST, SDT, or MR) make a difference in this factor?

Yeh, the kind of cashing will matter. What kind of game is it?

SDT is approx 17000 to 19000 per turn.
SST is 9000 to 11000 per turn.

You really can't compare alignment change to the amount of cash you will make on a constant basis. There are other factors that can change alignment, such as killing fighters if you are using a cashing script that moves throughout the universe to cash or furb. Also, the type of cashing your are using can vary a great deal when comparing cash made to alignment change.
I suppose you could take the method of cashing and the edit settings into consideration if you are attempting to estimate the amount of cash that is being made, but it would more or less be a rough estimate rather than an exact science.

It's a MBBS game with only 5% port regen, 10k universe, 20k turns. I'm guessing SDT is the cashing method and most likely not all 20k turns are being used for cashing. Since the price paid per unit for equipment by good ports is fairly constant and the alignment change is a function of the number of units stolen, I'm guessing that regardless of what cashing method is used, the credits earned per negative alignment point should be fairly constant. The exception of course would be megarob since you aren't stealing equipment. I realize that other actions can change alignment as well but based on daily logs and messages these should be minor and I'm just looking to get a ballpark estimate anyway.