You may want to act as your registered agent if you have an office with a street address in the state where you are incorporated. This will save you some money. However, if you need a different registered agent, most Corporate Filing Office websites list people or businesses that act as registered agents for that particular state. Also, the link will give you a list of national companies that offer registered agent services. These services generally charge from $100 to $200 per year for the service.
For more information on registered agent companies, visit: http://www.registered-agent-listings.com
Note: Most Secretary of State Websites will have a list of registered agents for that state.