Suggestion on registrar selection
If you are responding to an outside (e.g., customer) requirement to register an EMS, check what their specific requirements are, since not all registrars are accredited, either by the accreditor for the USA, ANAB , or by another country’s accreditation bodies.
There are no requirements within the USA, at least from the government, for using an accredited registrar. However, you may want to consider the value of a registration by a registrar with a solid reputation and formal credentials, versus a firm without such credentials. If you are reacting to a business requirement, such as a customer demand, it is usually a good practice to check on what that customer specifically wants.
The audit team the registrar sends should be staffed by professionals who have experience in your industry, or as close to it as possible.
You can negotiate. Factors to consider for negotiation include: cost and make-up of the audit team, and the amount of time the audit team will spend at your site. References can be important.
Also, consider contracting for a pre-registration audit, as it will help you see if you are as ready for the formal registration audit as you may think you are.