Ask Lawyer: How much litigation will cost you?
According to the Court Statistics Project article Estimating the Cost of Civil Litigation the cost of various types of cases could be estimated based on the number of hours spent by attorneys in such cases.
or see the graph below (from the same article) of Median Costs of Litigation by Case Type
It is better to use table and multiply on the hourly rate in your State or City because the hourly rate in different states varies substantially and the graph gives only very general idea of the cost. More precise data, including experts costs, can be obtained a different publication Hours Expended by Attorneys, Paralegals and Expert Witnesses to Complete Litigation Tasks by Case Type of the National Center for State Courts