You have a fiduciary responsibility to ensure that plan fees are reasonable as a plan sponsor. The best practice for meeting this fiduciary obligation is to go shopping. Ask a variety of potential vendors the same questions about what they charge for the services they provide. Obtain bids from the most promising vendors and chose your favorite.
Remember that plan participants and the Department of Labor may be interested in your shopping experience. Please document the process used for making your selections and the basis for doing so. This will demonstrate that you acted prudently to save money for plan participants.
Occasionally, you might want to, in effect, return what you purchased. You may find that you paid too much for a brand name or that the service was deficient. When this happens, it is time to go shopping again. When you shop around for a plan audit, please make sure the firm you select is a member of the AICPA Employee Benefit Plan Audit Quality Center.