Although mobile command units are expensive, those police departments that have purchased them view them as essential as a base of operations for a critical incident or as a means of crowd control at public events. Funding is a different issue for each agency. Some larger agencies have mobile command units built into their vehicle replacement plans, and other departments have used separate funding for their specialty vehicles. Regardless of funding mechanisms, the purchase of such an expensive vehicle is lengthy and complex. It involves research on companies, chassis, layouts, and equipment. An important step is to contact other agencies about their mobile command units, so as to determine the criteria involved in their selection and lessons they learned from their experience. An important component of the selection process is planning for the future by choosing the right chassis for current needs as well as built-in room for expansion. One manufacturer advises that a custom-built chassis is often a better choice than a commercial or school-bus chassis. The cost is virtually the same, since a ready-made chassis involves the cost of retrofitting. In addition to researching vehicle features and specifications, information should also be obtained on the companies being considered to manufacture the vehicle. This should include contacting references provided by each company. The bid process works much like the process used to buy any other major piece of equipment for an agency. Before and after the bid process, it is important to communicate clearly and in detail the features of the vehicle the agency wants to purchase. Companies typically involve agency representatives to view the vehicle in various stages of the building process. This should be done in order to confirm both to the company and the purchasing agency that the construction is meeting the agency's criteria. Most companies have drivers/trainers who will deliver the vehicle and then train whoever will be driving and operating it.