HELP Option Prices Variable by Usergroup

We want to modify option prices by usergroup but CS-Cart doesn’t allow that. So we are going to create a mod essentially creating a new table that is the same as the options variants table but with a usergroup_id field and then replace the function that pull in the option prices so it pulls from that table. It seems like a fairly simple mod if I could only find the function that reads the option prices! If anyone know what the function is called and which script it is in, lease throw me a bone!