I'd appreciate help in locating a free source of survey information concerning health benefit costs by employee.

There are a number of sources - some of which provide the direct answer and others require you to do some interpretation and manipulaton of numbers.

[Some provide have additional info at a modest fee]

Federal govt - HHS and Vital Statisticsn and many other similar sites there.
Society of Actuaries
EBRI
Dept of Labor
Intl Fndn of Employee Benefits

Your request raises a question in my mind: to what use are you going to put the data? If, for example, it is determined that, on a nationwide basis, the cost of a particular benefit, say inpatient physicians visits, is $X per month, how will you use that? It is not easily converted to a cost for any particular group.

I am currently engaged in a survey of health care plans for retired teachers and might have much of the data you are looking for. Feel free to call me at 517.322.6262.